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Full text of "Wastewater engineering and management plan for Boston harbor - eastern Massachusetts metropolitan area emma study, technical data volume 15: recommended plan and implementation program"

WASTEWATER ENGINEERING 
AND MANAGEMENT PLAN 

FOR 

50ST0N HARBOR - EASTERN MASSACHUSETTS METROPOLITAN AREA 

EMMA STUDY 

TECHNICAL DATA VOL. 15 
RECOMMENDED PLAN AND IMPLEMENTATION PROGRAM 




| DEER ISLAND WWTP SERVICE AREA 

| | NUT ISLAND WWTP SERVICE AREA 

| | UPPER NEPONSET WWTP SERVICE AREA 

H MIDDLE CHARLES WWTP SERVICE AREA 



OCTOBER 1975 



INDEX TO EMMA STUDY REPORTS 



BROCHURE 

SUMMARY REPORT 

MAIN REPORT 

TECHNICAL DATA VOLUMES 

1 PLANNING CRITERIA 

2 ENGINEERING CRITERIA 

3 INDUSTRIAL PROCESS WASTEWATER ANALYSIS AND 
REGULATION 

3A STUDY OF CERTAIN INDUSTRIAL WASTES 

3B STUDY OF WASTES FROM LARGE INDUSTRIES 

4 WATER ORIENTED WASTEWATER UTILIZATION CONCEPTS 

5 LAND ORIENTED WASTEWATER UTILIZATION CONCEPTS 

6 FORMULATION OF WASTEWATER UTILIZATION PLAN 

7 COMBINED SEWER OVERFLOW REGULATION 

8 URBAN STORMWATER MANAGEMENT 

8A APPENDIX TO URBAN STORMWATER MANAGEMENT 

9 MDC INTERCEPTOR AND PUMPING STATION ANALYSIS 
AND IMPROVEMENTS 

10 DEER ISLAND WASTEWATER TREATMENT PLANT ANALYSIS 
AND IMPROVEMENTS 

11 NUT ISLAND WASTEWATER TREATMENT PLANT ANALYSIS 
AND IMPROVEMENTS 

12 FINANCING AND MANAGEMENT 

13 IMPACT ANALYSIS AND EVALUATION 
13A BIOLOGICAL IMPACT ANALYSIS 
13B SOCIO-ECONOMIC IMPACT ANALYSIS 
13C HYGIENIC IMPACT ANALYSIS 

13D VISUAL, CULTURAL AND DESIGN IMPACT ANALYSIS 

14 PUBLIC INVOLVEMENT 

15 RECOMMENDED PLAN AND IMPLEMENTATION PROGRAM 

16 AGENCY REVIEWS 



COVER PHOTOGRAPH 

The cover photograph on this Technical Data Volume 
depicts the service area for each of the four wastewater 
treatment plants in the Recommended Plan. 



WASTEWATER ENGINEERING 

AND MANAGEMENT PLAN 

FOR 

BOSTON HARBOR - EASTERN MASSACHUSETTS METROPOLITAN AREA 

EMMA STUDY 



TECHNICAL DATA VOL. 15 
RECOMMENDED PLAN AND IMPLEMENTATION PROGRAM 



FOR THE 
METROPOLITAN DISTRICT COMMISSION 



COMMONWEALTH OF MASSACHUSETTS 



BY 



METCALF & EDDY, INC. 



OCTOBER 1975 



Digitized by the Internet Archive 
in 2013 



http://archive.org/details/wastewaterengine15mass 



TABLE OF CONTENTS 

Page 

LIST OF TABLES 

LIST OF FIGURES 

REPORT 

CHAPTER 1 - INTRODUCTION 1-1 

General 1-1 

Report Structure 1-1 

CHAPTER 2 - COMBINED SEWER OVERFLOW 

REGULATION 2-1 

General 2-1 

Policy 2-2 

Program Recommendations 2-2 

Consideration of Water Quality Needs 2-3 

Recommended Course of Action 2-5 

CHAPTER 3 - SATELLITE WASTEWATER TREATMENT 

PLANTS 3-1 

General 3-1 
Proposed Upper Neponset River T •eatment 

Plant 3-3 
Proposed Middle Charles River T 'eatment 

Plant 3-3 

Basic Design Criteria 3-3 

Site Layouts 3-12 

Costs 3-15 

Sludge Management Techniques 3-16 

CHAPTER 4 - INTERCEPTOR, PUMPING STATION AND 

HEADWORKS IMPROVEMENTS 4-1 

General 4-1 

Existing System 4-1 

North Metropolitan Sewerage System 4-1 

South Metropolitan Sewerage System 4-4 

Interceptor Relief Requirements 4-4 

Headworks Analysis and Improvements 4-23 



TABLE OF CONTENTS (Continued) 



Page 

CHAPTER 5 - NUT ISLAND TREATMENT PLANT 

IMPROVEMENTS 5-1 

General 5-1 

Existing Facilities 5-1 

Primary Expansion 5-^ 

Secondary Extension 5-13 

Site Requirements 5-15 

Phased Development and Costs 5-19 

CHAPTER 6 - DEER ISLAND TREATMENT PLANT 

IMPROVEMENTS 6-1 

General 6-1 

Existing Facilities 6-1 

Adequacy of Existing Facilities 6-3 

Primary Expansion 6-3 

Secondary Extension 6-10 

Site Requirements 6-13 

Phased Development and Costs 6-14 

Operation and Maintenance Costs 6-17 

CHAPTER 7 - CONSTRUCTION STAGING AND COST 

DISTRIBUTION 7-1 

General 7-1 

Cost Bases 7-1 

Annual Operation and Maintenance Costs 7-3 

Cost Apportionment and Allocation 7-3 

Apportionment of Costs 7-4 

Allocation of Costs to Industries 7-5 

CHAPTER 8 - FINANCING^ AND MANAGEMENT 8-1 

General 8-1 

Financing 8-1 

Management 8-2 



ii 



LIST OF TABLES 



Table Page 

2-1 Summary of Capital and Operation and 
Maintenance Costs for Combined Sewer 
Overflow Regulation Alternatives 2-10 

2-2 Overflow Abatement Alternatives Special 

Projects 2-13 

3-1 Plant Loads 3-4 

3-2 Basic Design Criteria - Upper Neponset 
River Advanced Wastewater Treatment 
Plant 3-6 

3-3 Basic Design Criteria - Middle Charles 
River Advanced Wastewater Treatment 
Plant 3-8 

3-4 Construction Cost - Upper Neponset River 

Wastewater Treatment Plant 3-16 

3-5 Construction Cost - Middle Charles River 

Wastewater Treatment Plant 3-17 

3-6 Annual Operation and Maintenance Cost - 

Upper Neponset River Wastewater Treatment 
Plant 3-18 

3-7 Annual Operation and Maintenance Cost - 
Middle Charles River Wastewater 
Treatment Plant 3-18 

3-8 Sludge Quantities 3-19 

4-1 Existing North Metropolitan Sewerage 

System (Deer Island) Service Area 4-3 

4-2 Existing South Metropolitan Sewerage 

System (Nut Island) Service Area 4-5 

4-3 Relief Requirements Under the Recommended 

Plan 4-6 

4-4 Design Flows for MDC Interceptors 

Requiring Relief 4-12 



iii 



LIST OF TABLES (Continued) 



Table Page 

4-5 Estimated Cost of Interceptor Improvements 

Required Under the Recommended Plan 4-17 

4-6 Interceptor Requirements for New Communi- 
ties Under the Recommended Plan 4-18 

4-7 Future Capacity Requirements for Dry 

Weather Flows - 2000 4-19 

4-8 Estimated Cost for Rehabilitation or 

Replacement of MDC Pumping Stations 4-21 

4-9 Pumping Stations - Annual Operation and 

Maintenance Costs 4-22 

5-1 Basic Design Criteria Nut Island Primary 

Expansion 5-5 

5-2 Basic Design Criteria Secondary 

Extension - Nut Island 5-14 

5-3 Construction Cost - Nut Island Wastewater 

Treatment Plant 5-18 

5-4 , First-Phase Construction Costs 5-20 

5-5 Second-Phase Construction Costs 5-21 

5-6 Annual Operation and Maintenance Costs 5-22 

6-1 Basic Design Criteria Deer Island 

Treatment Plant Primary Expansion 6-4 

6-2 Basic Design Criteria Deer Island 

Treatment Plant Secondary Extension 6^11 

6-3 Advantages and Disadvantages of the 

Recommended Plan 6-16 

6-4 Construction Cost - First Phase 6-17 

6-5 Construction Cost - Second Phase 6-17 

6-6 Annual Operating and Maintenance Cost 6-l8 



iv 



LIST OP TABLES (Continued) 



Table Page 

7-1 Summary of Annual Operation and 

Maintenance Costs 7-3 

7-2 Estimated Percent of Capital Costs Dis- 
tributed to Flow, BOD and SS for the 
Recommended Facilities 7-^ 

7-3 Distribution of Operation and Main- 
tenance Costs to Flow, BOD and SS 7-5 

7-4 Estimated Percent of Total Costs 

Attributed to Flow, BOD and SS for 

Cities and Towns in the MDC Service 

Area 7-6 

7-5 Estimated Percent of Apportioned 

Community Costs Attributed to Flow, 
BOD and SS Originating from Major 
• Industries 7-8 



LIST OF FIGURES 



Figure Page 

1-1 Existing and Ultimated MDC Service Areas 1-2 

1-2 Wastewater Treatment Plant Service 

Areas - Recommended Plan 1-3 

2-1 Combined Sewer Area Separated by 

Receiving Waters 2-4 

2-2 Satellite Regulation Facilities and 

Collection Systems in Alternative 1 2-7 

2-3 Moon Island Tunnel Plan with Satellite 
Regulation Facilities and Collection 
Systems in Alternative 2 2-8 

2-4 Modified Moon Island Plan with Satellite 
Regulation Facilities and Collection 
Systems in Alternative 3 2-9 

3-1 Treatment Train and Effluent Criteria for 
AV/T - Continuous Nitrification and Phos- 
phorus Removal 3-2 

3-2 Upper Neponset River WWTP Layout 3-13 

3-3 Middle Charles River WWTP Layout 3-14 

4-1 Areas Served by the Existing Metropolitan 
Interceptor Systems and the Deer and Nut 
Island Wastewater Treatment Plants 4-2 

4-2 Interceptor Relief Requirements Under Bound in 
Recommended Plan Back 

5-1 Treatment and Effluent Criteria for 

Secondary Treatment 5-2 

5-2 Flow Diagram - Nut Island Wastewater 

Treatment Plant 5-3 

5-3 Diagrammatic Layout Revised Preliminary 
Treatment Facilities - Nut Island Waste- 
water Treatment Plant 5-9 



VI 



LIST OF FIGURES (Continued) 



Figure Page 

5-4 Nut Island Wastewater Treatment Plant - 

Outfall System 5-11 

5-5 Nut Island WWTP Layout - Recommended 

Plan 5-17 

6-1 Flow Diagram - Deer Island Wastewater 

Treatment Plant 6-2 

6-2 Deer Island Wastewater Treatment Plant - 

Outfall System 6-8 

6-3 Deer Island WWTP - Site Option 5 - 

Recommended Plan 6-15 

7-1 MDC Construction Staging Program for 
Wastewater Management Projects - 
Recommended Plan 7-2 



Yll 



REPORT 



CHAPTER i 
INTRODUCTION 



General 

There are 43 cities and towns in the Metropolitan 
Sewer District (MSD) which now serves almost 2 million 
people from an area greater than 400 square miles generally 
as shown on Figure 1-1 . 

The MSD facilities include approximately 225 miles 
of trunk sewers, serving nearly 5,000 miles of local sewers. 
The District has 12 pumping stations, four headworks, and 
two large primary treatment plants at Deer Island and Nut 
Island. These plants have an average treatment capacity 
of more than 450 mgd (million gallons per day), with a 
combined capability of handling maximum flows at the rate 
of 1.2 bgd (billion gallons per day). 

Completing the major components of the wastewater 
transport and disposal system in the MSD service area are 
numerous (of which 68 are major) combined sewer overflows 
in five member communities serving an area of 36 square 
miles and 900,000 people, nearly one-half of the MSD 
served population. 

Under the Recommended Plan, the MSD will be expanded 
from the current 43 members to a total of 51 member commu- 
nities as shown on Figure 1-1. In addition to expansion of 
the overall MSD area 3 the Recommended Plan proposes decen- 
tralization of the area served by the Nut Island Treatment 
Plant by construction of two satellite treatment plants 
within its service area for sewerage service to areas 
shown on Figure 1-2. 

Various additions and improvements are necessary in 
order to ensure adequate facilities to meet the requirements 
of this expanded system and are presented in this report as 
they relate to the Recommended Plan. 

Report Structure 

As shown on the inside cover, the study results are 
presented in a series of volumes. 

This report is Technical Data Vol. 15 , Recommended 
Plan and Implementation Program and covers the recommenda- 
tions made as a result of the 2MMA Study. 



1-1 




FIG. 11 EXISTING AND ULTIMATE MDC SERVICE AREAS 







FIG. 1-2 WASTEWATER TREATMENT PLANT SERVICE \RE\S - 

RECOMMENDED PLAN 



The background relating to the development of the 
various recommendations and their costs are presented in 
the appropriate Technical Data Volumes pertaining to each 
specific topic, and the reader is referred to them for an 
in-depth presentation of the material. 

While all items presented in this report are inter- 
related, early chapters of this report deal with specific 
items of the sewerage system while the later chapters deal 
with the costs of the program and the recommendations for 
financing and managing the system. 



1-4 



CHAPTER 2 
COMBINED SEWER OVERFLOW REGULATION 



General 

Boston Harbor and the rivers tributary to it have 
been the prime resources responsible for the early growth 
of the Boston metropolitan area. These waters have for 
many years served industrial, commercial and recreational 
activities providing, among others, the service of waste- 
water disposal. This has resulted in the deterioration of 
these resources to the degree where competing uses have 
suffered. 

One of the major causes of pollution recognized for 
many years has been overflow from combined sewers. Ini- 
tially, combined sewers were built to convey sewage and 
stormwater, two urban nuisances, to the nearest watercourse 
In 1884, the Boston Main Drainage Works were completed 
consisting of interceptors collecting much of this pollu- 
tion and diverting it to the then newly constructed Moon 
Island facilities for discharge away from the shoreline 
in deeper waters. By about 1900, additional interceptors 
were constructed which diverted stream and shoreline 
discharges to deeper waters off Deer and Nut Islands 
constituting respectively the North Metropolitan Sewerage 
District and the South Metropolitan Sewerage District. 

These interceptors were generally sized to carry 
all dry-weather flow plus an additional allowance for 
stormwater. The stormwater was believed to dilute the 
dry weather flow to the point where overflows would not 
adversely affect the quality of the receiving waters. 

One of the most comprehensive early studies on the 
conditions in the Boston Harbor and its tributary streams 
was reported in Massachusetts House Document No. 1600 of 
1936.* At that time, no treatment was provided for any 
discharges to the Boston Harbor. 

Findings at that time demonstrated that bacterial 
pollution, floating solids, slick and sludge deposits were 



* Report of the Special Commission on the Investigation of 
the Discharge of Sewage into Boston Harbor and its Tribu- 
taries , Massachusetts House Document No. 1600. December 
1936. 



2-1 



th^ factors related to objectionable water quality condi- 
tions, but in no case did results show that a nuisance 
would result from lack of oxygen. 

The report T s recommendations pertinent to untreated 
overflows into the receiving waters included provisions 
for treatment at the main interceptor outlets, preparation 
of adequate works to remove causes of overflow, and preven- 
tion of bathing along the waterfront of Boston Harbor, its 
estuaries and tributaries except at such points as met 
with the approval of health agencies. 

Today, primary treatment is being provided to the 
intercepted flows at the Deer and Nut Island treatment 
plants. However, numerous locations exist in the Boston 
Harbor area where, during rain storms, combined sewage 
overflows into the receiving waters untreated as it did in 
1936. 

Recognizing the importance of this source of pollu- 
tion, the New England states and the EPA have established 
the following policy and program recommendations on 
combined sewers and urban runoff. 

Policy 

"The New England states and the EPA recognize 
combined sewer discharges and urban runoff as a 
major water pollution control problem in New 
England. Joint State-Federal water pollution 
control programs should place special emphasis on 
the control and elimination of these discharges 
through construction and operation and maintenance 
programs, giving priority to those discharges 
affecting bathing and shellfish. EPA should 
continue funding demonstration projects. In addi- 
tion, the states and EPA recognize the necessity 
for programs to minimize the pollutional impact 
of urban storm runoff." 

Program Recommendations 

1. "Accelerate Municipal Planning for Combined 
Sewer Control. 

2. Accelerate Municipal Programs for Operation and 
Maintenance and Construction to Control or 
Eliminate Combined Sewer Discharges. 



2-2 



3. Give Appropriate Priority to Combined Sewer 
Correction in the State-Federal Planning Process 
and Construction Grants Program. 

4. Clarify the Types of Treatment Required for 
Combined and Storm Sewer Discharges. 

5. Alleviate Pollution from Urban Runoff in Design- 
ing Combined Sewer Correction Systems and by 
Encouraging Local Land Management Practices and 
Regulatory Measures. 

6. Achieve Consistent Policies and Design Standards 
for Combined Sewer Correction Programs among 
State and Federal Agencies Involved in Combined 
Sewer Correction." 

"Joint State-Federal Policy and Program Recommenda- 
tions for Four Key Determinants of Water Quality in 
New England," Region 1, U. S. Environmental Protec- 
tion Agency and New England Interstate Water Pollu- 
tion Control Commission, June 197^ • 

Consideration of Water Quality Needs 

Although the Boston Harbor and its tributary streams 
are one, interrelated entity, conditions and uses vary 
throughout. Recognizing this, the Massachusetts Division 
of Water Pollution Control has set differing standards in 
sections of the Boston Harbor area encompassing both fresh 
and salt waters.* 

In considering water quality problems and remedial 
needs related to combined sewer overflows, the areas 
tributary to sections of the Boston Harbor have been 
grouped as shown on Figure 2-1. General grouping are: 

Dorchester Bay, including overflows from Dorchester 
and South Boston; 

Charles River Basin, including the Back Bay Fens 
and existing regulation facilities; 

Neponset River Estuary, including overflows from 
Dorchester; and 



* Boston~*Harbor Pollution Survey , Division of Water Pollu- 
tion Control, Massachusetts Water Resources Commission, 
August 1970. 



2-3 



LEGEND 



• 



4 






4500 9000 13500 



SCALE IN FEET 



COMBINED SEWER AREAS 

EXISTING COMBINED SEWER OVERFLOWS 

DORCHESTER BAY 

CHARLES RIVER BASIN 

INNER HARBOR 

NEPONSET RIVER 

CHELSEA AND MYSTIC RIVERS 

CONSTITUTION BEACH 

TRIBUTARY TO COTTAGE FARM STATION t 





FIG. 2 1 COMBINED SEWER AREA SEPARATED BY RECEIVING WATERS 



Inner Harbor, including main shipping areas of the 
Harbor and the estuary portions of the Charles and 
Mystic Rivers. 

Detailed discussion relating to these groupings is 
presented in Chapter 6 of Technical Data Vol. 7. 

Recommended Course of Action 

The recommended course of action is a decentralized 
system based on combined sewer regulation facilities de- 
signed to provide the following treatment: 

, 1. Chlorination with 15 minutes detention under 
design storm conditions (also providing for 
removal of solids and other pollutants through 
capture or sedimentation). 

2. Screening for removal of large solids. 

3. Skimming for removal of floatables. 

A decentralized plan would continue present remedial 
practices . 

Such a plan would allow staged implementation 
with immediate opportunities for solving high priority 
problem areas. 

The degree and nature of the improvements could be 
geared to specific needs of each location and the extent 
of regulation provided could be carried out in stages so 
that advantage can be taken of evolving technologies in 
combined sewer overflow regulation and treatment. Treat- 
ment options under research and development have centered 
around physical treatment concepts of concentration, 
screening, sedimentation, flotation, filtration and 
disinfection. 

The largest benefits in pollution reduction in 
decentralized systems will probably come from first flush 
capture and diversion to the dry-weather flow treatment 
plant and through sedimentation, skimming and disinfection 
as a result of detaining overflows. 

A drawback in decentralized systems has been space 
requirement in high density land-use areas. This is in 
part being overcome by designs involving multiple use of 
land. For example, placement of overflow regulation 



2-5 



facilities under parking garages, recreational facilities, 
parks, bus stops, and the like is being practiced. 

Another key factor in the decentralized approach is 
the selection of overflow groupings and the selection of 
overflow regulation facility discharge points. In the 
Charles River Basin area, overflow discharge concentration 
is dictated to some extent by overflow conduit arrangements 
and facilities originally constructed for the abatement of 
overflows there. The prime objectives in this location 
would be to make maximum use of existing facilities and 
provide necessary treatment levels. In the Back Bay Fens, 
improvement of circulation would be an added objective. 

Opportunities for alternative arrangements in a 
decentralized plan exist as shown by the three alternatives 
presented in detail in Technical Data Vol. 7 and as briefly 
discussed below. 

Alternative 1, as shown on Figure 2-2 - Satellite 
Regulation Facilities, consolidates the overflows into 
10 groups to be individually collected and treated prior 
to discharge. Alternative 2, as shown on Figure 2-3 - 
Moon Island Tunnel Plan, further consolidates the three 
groups of overflows in Alternative 1 discharging to 
Dorchester Bay and Fort Point Channel and transports them 
via deep tunnels to Moon Island for treatment. Alterna- 
tive 3, as shown on Figure 2-4 - Modified Moon Island Plan, 
also consolidates discharges to Dorchester Bay and trans- 
ports -them to Moon Island through the existing Dorchester 
Bay Tunnel. Flow in excess of the existing tunnel system 
would be treated and discharged at a Columbia Point regu- 
lation facility. 

Water quality analysis of the three decentralized 
alternatives demonstrates that relocation of overflows 
away from sensitive water quality areas accompanied by 
storage and treatment is the best approach to abate 
combined sewer overflows. Alternative 2 records the most 
favorable water quality results. 

From a cost standpoint, as summarized in Table 2-L, 
all alternatives have the same order-of-magnitude costs 
with Alternative 1 the lowest in terms of capital cost 
and Alternative 2 the lowest in terms of operation and 
maintenance cost. 



2-6 



• 



4500 9000 13500 



SCALE IN FEET 



LEGEND 
COMBINED SEWER AREAS 
EXISTING DETENTION FACILITIES 
PROPOSED REGULATION FACILITIES 
PROPOSED COLLECTION CONDUITS 
LIMIT OF TRIBUTARY AREA 

\J CH>>f 



4 




FIG. 2-2 SATELLITE REGULATION FACILITIES AND COLLECTION SYSTEMS 

IN ALTERNATIVE 1 



* 




4500 9000 13500 



SCALE IN FEET 



LEGEND 
COMBINED SEWER AREAS 
EXISTING DETENTION FACILITIES X* 

PROPOSED REGULATION FACILITIES 1flB 
PROPOSED COLLECTION CONDUITS «— 
PROPOSED COLLECTION TUNNELS «"™ 



LIMIT OF TRIBUTARY AREA 




FIG. 2 3 MOON ISLAND TUNNEL PLAN WITH SATELLITE REGULATION 
FACILITIES AND COLLECTION SYSTEMS IN ALTERNATIVE 2 



• 



4500 9000 13500 



SCALE IN FEET 



LEGEND 
COMBINED SEWER AREAS 
EXISTING DETENTION FACILITIES 
PROPOSED REGULATION FACILITIES 
PROPOSED COLLECTION CONDUITS 
EXISTING COLLECTION CONDUITS 
LIMIT OF TRIBUTARY AREA 



f 







FIG. 2-4 MODIFIED MOON ISLAND PLAN WITH SATELLITE REGULATION 
FACILITIES AND COLLECTION SYSTEMS IN ALTER \ \TIVE 3 



TABLE 2-1. SUMMARY OF CAPITAL AND OPERATION 

AND MAINTENANCE COSTS FOR COMBINED SEWER 

OVERFLOW REGULATION ALTERNATIVES 



,.. x Operation and maintenance 

Capital cost, } costal) million dollars 

Alternative million dollars per yr 

1 279 3.9 

2 299 3.7 

3 307 3.8 



1. January 1975 costs JeM 2200). 



The following course of action presents outline 
plans of study for facilities planning projects involving 
combined sewer overflow regulation. 

Dorchester Bay Combined Sewer Overflow Regulation 
Proj ect . This project would be for a facilities plan on 
the regulation of overflows in the Dorchester Bay area and 
should include: 

1. Refinement of the combined sewer system models. 

2. Rainfall-runoff-overflow measurements in a 
selected controlled test area for model verifi- 
cation and parameter correlation. These measure- 
ments should extend into the receiving water. 

3. Detailed consideration of special pollution 
sources, such as hospitals. 

*l. Refinement and verification of Harbor water 
quality simulation models for evaluation of 
potential discharge locations. 

5. Evaluation of alternatives. Consideration of 
diverting discharges in the direction of the 
Neponset River Estuary does not appear desirable 
However, alternatives of discharges in the 
Inner Harbor area and around Moon Island in the 
direction of President Roads should be investi- 
gated. Alternatives should be evaluated on 
their performance over a longer hydrologic 
record so that appropriate design hydrology 
can be used in each case. 



2-10 



6. Detailed inventory and evaluation of the feasi- 
bility of upgrading the Moon Island facilities. 

7. Site selection and preliminary engineering. 

8. Consideration of multipurpose uses of land. 

Charles River Basin Combined Sewer Overflow Regula- 
tion Project . This project should involve evaluation of 
the entire system related to combined sewer overflows 
tributary to the basin once the New Dam and related facil- 
ities are completed. Included should be the Back Bay Fens 
area and the as yet unconnected overflows along the Charles 
River Basin. Facilities planning should emphasize an 
operating system towards optimum use of existing facilities 
along with treatment required at new facilities. The major 
project tasks should be: 

1. Refinement of combined sewer models to the 
extent necessary so that all existing overflow 
conduits can be evaluated in detail. 

2. Rainfall-runoff-overflow measurements in a 
selected controlled test area for model verifi- 
cation and parameter selection. Since the 
basin essentially acts as a reservoir, exclusion 
of pollutants should be the objective rather 
than searching for an optimum discharge point. 

3. Consideration of the state-of-the-art in storage- 
treatment concepts for overflows discharged 
above the new Charles River Dam. 

4. Consideration of new regulator technologies for 
upgrading such facilities at the existing over- 
flow conduits. 

5. Evaluation of alternatives. Optimum solutions 
in this project area appear to be an operating 
system that would make maximum use of existing 
facilities in such a way that first flush 
effects are transported to facilities below the 
Dam for treatment and discharge, or are stored 
and treated more extensively prior to discharge 
into the basin, or are stored and diverted to 
the Deer Island Treatment Plant. Performance 
of alternatives under longer term hydrologic 
records must be part of the evaluation. In the 
development of alternatives, unconnected over- 
flows must be included. Similarly, existing 



2-11 



overflow conduits should become part of the 
operating system. 

6. Incorporation of Back Bay Fens recreation objec- 
tives in plan selection. In the development of 
alternatives j the problems and objectives of the 
Back Bay Fens water resource should be incor- 
porated into the project. For example, solving 
the Fens circulation problems should be part 

of the objectives of combined sewer overflow 
regulation there. 

7. Site selection and preliminary engineering. 

8. Consideration of multipurpose use of land. In 
this case, multiuse alternatives would be 
especially important due to the high recrea- 
tional potentials in the Back Bay Fens and 
along the basin. 

N eponset River Combined Sewer Overflow Regulation 
Proj ect . Due to its location, alternatives in this project 
area would primarily address the search for a cost-effec- 
tive solution to minimize pollution discharges. The 
project tasks should include: 

1. Refinement of the combined sewer system models. 

2. Evaluation of alternatives. Again, performance 
on the basis of longer range hydrologic data 
should be evaluated. 

3. Site selection and preliminary engineering. 

Inner Harbor Combined Sewer Overflow Regulation 
Proj ect . It appears that consolidation of overflows in 
the Inner Harbor area will be primarily directed at over- 
coming constraints associated with space needed for conduits 
and regulation facilities. Therefore, primary efforts in 
this area should be directed at the technical problems of 
conduit location, regulator design and discharge pipe 
location. The facilities plan should cover, among other 
things, the following: 

1. Refinement of combined sewer system models. 

2. Detailed consideration of industrial pollution 
sources . 

3. Evaluation of consolidation alternatives. 



2-12 



4. Site selection and preliminary engineering;. 

5. Consideration of multipurpose use of land. 

6. Evaluation of overflows in the Constitution 
Beach area as a special case. 

Special Projects . The special projects for combined 
sewer overflows should be evaluated in accordance with 
recommendations made in Table 2-2. 



TABLE 2-2. 



OVERFLOW ABATEMENT ALTERNATIVES 
SPECIAL PROJECTS 



Outfall 

No. Location 



Abatement alternative 
or existing condition 



63 



5,7 



93,11,23, 
29,39,47, 
55,64 



88,90 



119 



95 



Brighton 



Cambridge 



Charlestown 



Somerville 



Chelsea 



East Boston 



South Boston 



Connect overflow to South 
Charles Relief Sewer for 
diversion to Cottage Farm 
Facility. 

To be connected to the Cottage 
Farm Facility via the North 
Charles Relief Sewer upon its 
completion. 

These outfalls are to be sepa- 
rated under urban renewal 
projects directed by the 
Boston Redevelopment Authority. 

These outfalls are treated by 
the Somerville Chlorination 

Facility. 

The tributary area to this 
outfall could be separated, 
possibly under an urban renewal 
project, or the overflow can 
be diverted to chlorination- 
detention tank No. 6. 

The tributary area to this 
outfall could be separated or 
the overflow could be diverted 
to tank No. 7. 

There is no overflow during a 
one-year storm at this loca- 
tion. 



2-13 



Other special studies, as mentioned under several 
of the above projects, should be sample area monitoring 
of the rainfall-runoff-overflow process. Evaluation of 
such for purposes of verifying and modifying parameters 
for combined sewer overflow simulation would be carried 
out. Similarly, in the case of overflows in the beach 
areas, further detailed studies of that Boston Plarbor area 
receiving waters should be carried out to aid in selection 
of optimum discharge locations. 



2-14 



CHAPTER 3 
SATELLITE WASTEWATER TREATMENT PLANTS 



General 

As mentioned in Chapter 1, the Technical Subcommittee 
after reviewing the findings of this investigation and 
holding a series of public meeting have recommended the 
construction of two satellite treatment plants. These 
satellite plants, one located on the Upper Neponset River 
and the other on the Middle Charles River, would be within 
the present service area of the Nut Island Treatment Plant 
as shown on Figure 1-2. The advantages of such an arrange- 
ment are the potential for augmenting low flows in the 
Neponset and Charles rivers, and the benefits that would be 
realized by reducing the wastewater inflow to the Nut 
Island Treatment Plant. 

Because of their inland location and the characteris- 
tics of the rivers into which they discharge, both satellite 
plants must provide advanced treatment. A treatment train 
selected for this is presented on Figure 3-1 and is discussed 
in Technical Data Vol. 2. A treatment train consists of 
various unit processes which are so arranged that each 
following unit process produces an effluent of higher 
quality. In this case, the treatment train provides, in 
sequence, preliminary, primary and secondary treatment, 
nitrification, filtration, chlorination and postaeration. 
Removal of phosphate is achieved by chemical precipitation 
within the secondary treatment unit process. These unit 
processes will produce an effluent with a monthly average 
limit of 5 mg/L (milligrams per liter) of BOD^ (5-day 
biochemical oxygen demand), 5 mg/L of SS (suspended solids), 
and a phosphorus concentration of less than 1 mg/L expressed 
as P. The process is designed to oxidize ammonia nitrogen 
(NH3-N) to nitrate (NO3-N), thus reducing the nitrogenous 
oxygen demand on the receiving stream. 

The above treatment requirements were initially 
selected on the basis of experience under similar condi- 
tions pending results of basin planning studies which are 
being conducted for purposes of establishing these treat- 
ment requirements for the satellite plants. 

Initial analysis of the Charles River Basin Plan, in 
preparation by the Massachusetts Division of Water Pollu- 
tion Control, Water Quality and Research Section, indicates 
that in the case of the Middle Charles Treatment Plant, the 



3-1 








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selected treatment process would meet Class Bl requirements. 
To achieve Class B classification requirements, treatment 
beyond normal wastewater treatment processes would be 
necessary. 

The intended use of Class B and Bl waters is the 
same. In addition, the criteria for Class B and Bl waters 
is the same with the exception of the dissolved oxygen 
requirement which is less stringent in the case of Class Bl 
waters . 

Proposed Upper Neponset River Treatment Plant 

This advanced treatment facility would be located 
in the Canton-Norwood area. It would treat approximately 
25.2 mgd in the year 2000 from the Towns of Canton, Norwood, 
Walpole, Sharon and Stoughton serving an estimated popula- 
tion of 130,900. This facility would reduce the service 
area of the Nut Island plant and keep reclaimed wastewater 
as far upstream in the Neponset River basin as possible. 

Proposed Middle Charles River Treatment Plant 

The middle reach of the Charles River would be the 
location for an advanced treatment facility to serve the 
Towns of Wellesley, Framingham, Ashland, Hopkinton, Natick, 
and Southborough as well as parts of Dover and Sherborn when 
sewerage is provided there. It would serve an estimated 
population of 179,300 by the year 2000. This 31.0-mgd 
facility would reduce flows to the Nut Island plant and 
help retain reclaimed wastewater in its basin of origin, 
while adding flows to the Charles River in dry seasons. 
The treatment facilities which are in various stages of 
implementation in the Medfield, Medway and Milford areas 
should also benefit the river. 

Pertinent data for each of these facilities is 
presented in the following sections of this chapter. 

Basic Design Criteria 

In this section, the plant loads are set forth, the 
facilities that would be provided at each plant are des- 
cribed, and a site layout for each plant is developed. 

Plant Loads . Table 3-1 presents the estimated loads 
for both the Upper Neponset and Middle Charles plants in 
terms of flow, BOD5, SS, NH3-1N, and PO^-P loads. The 
estimated loads are given for 2000, the design year, and 
also for the year 2050. 



3-3 



The flows given in Table 3-1 have been developed in 
accordance with the procedures described in Technical Data 
Vol. 2. The average day dry-weather flow (average day) 
allows for residential, commercial, minor and major indus- 
trial wastewater flows, and an average rate of infiltration 
Major industrial wastewater flows were determined by actual 
survey and exclude waters used for cooling purposes. The 
peak flow was determined by applying appropriate peaking 
factors to the average dry-weather flows from each source, 
and includes an allowance for peak wet-weather infiltration 



TABLE 3-1. PLANT LOADS 



2000 design 2050 



Upper Neponset River Plant 

Flow, mgd 

Average day 25.2 35.2 

Peak 67.4 82.4 

BOD c , lb/day 

Average day 42,000 66,000 

Peak 84,000 132,000 

SS, lb/day 

Average day 37,500 59,000 

Peak 75,000 118,000 

MH 3 -M, lb/day 

Average 4,400 6,200 

PO^-P, lb/day 

Average 2,600 3,500 

Middle Charles River Plant 

Flow, mgd 

Average day 31 45.6 

Peak 75.6 101 



BOD 



5 , lb/day 

Average day 57,400 87,290 

Peak 114,800 174,580 

3-4 



TABLE 3-1 (Contirued). PLANT LOADS 



2000 design 2050 



SS, lb/day 

Average day 47,400 73,650 

Peak 94,800 147,300 

NH3-N, lb/day 

Average 5,430 7,990 

P0 4 -P, lb/day 

Average 3,100 4,600 



Major and minor industrial, commercial and residen- 
tial sources were taken into consideration in determining 
pollutant loads (BOD5 and SS). Major industrial loads were 
determined by actual survey. Other sources were provided 
for by allowing for a concentration in the incoming waste- 
waters of 200 mg/L for both pollutants. 

The NH3-N and PO^-P loads were derived by estimating 
that the incoming wastewaters would contain concentrations 
of approximately 21 mg/L of NHo as N and 12 mg/L of PO^ 
as P. These values are typical for wastewater treatment 
plants that serve essentially residential areas. 

Design Criteria . Tables 3-2 and 3-3 present the 
basic design criteria that were used in selecting the 
facilities that are recommended for the Upper Neponset and 
Middle Charles River plants, respectively. The following 
discussion covers both plants since the process units and 
their sequential arrangement are similar. As previously 
noted, the recommended treatment train, as shown on Figure 
3-1, provides preliminary, primary and secondary treatment, 
nitrification, filtration, chlorination and postaeration. 

Treatment Processes . The treatment processes 
were selected as those judged best for the satellite 
plants on the basis of preliminary information for purposes 
of estimating costs and determining area requirements. 
During facilities planning, these and other processes 
would be investigated in detail in ordar to select a final 
cost-effective treatment process. 



3-5 



Preliminary treatment, which has the function of 
removing grit and other particles of similar characteris- 
tics from the incoming wastewater, would be accomplished by 
aerated grit chambers. For satisfactory operation, these 
units are designed to provide not less than three-minutes 



TABLE 3-2. BASIC DESIGN CRITERIA - UPPER NEPONSET 
RIVER ADVANCED WASTEWATER TREATMENT PLANT 



000 desi gn 2050 



Aerated Grit Chambers 



Number of units 






2 


3 


Unit length, ft 






48 


48 


Unit width, ft 






17 


17 


Unit depth, ft 






12 


12 


Overflow rate, gpdA 


;q 


ft 






Average day 






15,^00 


14,400 


Peak 






41,300 


33,700 


Detention time, min 










;ik 






3.1 


3.8 


Prime ?y Tanks 










Number of units 






6 


8 


Type 






Circular 


Circular 


Diameter, ft 






85 


85 


Overflow rate, gpdA 


jq 


ft 






Average day 






740 


775 


Peak 






1,980 


1,820 


Aeration Tanks 











BOD5, lb/day 

Average day 

Peak 
Number of units 
Unit length, ft 
Unit width, ft 
Unit length, ft 
Loading, lb of BODr/1,000 cf 

Average 

Peak 

Secondary Settling Tanks 

Plow, mgd 

Average day 25.2 35.2 

Peak 67.4 82.4 

i. umber of units 6 8 

3-6 



31,500 




49, 


,500 


63,000 




99, 


,000 


4 






6 


208 






208 


52 






52 


15 






15 


48. 


6 




50.8 


97. 


2 




101.7 



TABLE 3-2 (Continued). BASIC DESIGN CRITERIA - UPPER 
NEPONSET RIVER ADVANCED WASTERVv'ATER TREATMENT PLANT 





2000 design 


2050 


Type 


Circular 


Circular 


Diameter, ft 


110 


110 


Overflow rate, gpd/sq ft 






Average day 


440 


460 


Peak 


1,180 


1,080 


Nitrification Reactors 







NH3-N load, lb/day 

Average 
Number of units 
Unit length, ft 
Unit width, ft 
Unit depth, ft 

Nitrification Settling Tanks 



4,400 

4 

192 

48 

15 



Number of units 
Unit length, ft 
Unit width, ft 
Filtration rate, gpm/sq ft 
Average 

Chlorine Contact Chambers 

Flow, mgd 

Average day 

Peak 
Number of units 
Length of unit, ft 
Width of unit, ft 
Depth of unit, ft 
Detention time, min 

Average day 

Peak 



6 
32 
32 



2.9 



25.2 
67.4 
2 
100 
32 
15 

41.1 
15.4 



6,200 

6 

192 

48 

15 



Flow, mgd 






Average day 


25.2 


35.2 


Peak 


67.4 


82.4 


Number of units 


<-- 



8 


Type 


Circular 


Circular 


Diameter, ft 


120 


120 


Overflow rate, gpd/sq ft 






Average . 


370 


390 


Peak 


1,000 


910 


Multi-Media Filters 







8 
32 

32 



35.2 
82.4 
2 
100 
40 
15 

36.8 
15.7 



3-7 



TABLE 3-3. BASIC DESIGN CRITERIA - MIDDLE CHARLES 
RIVER ADVANCED WASTEWATER TREATMENT PLANT 

2000 design 2050 

Aerated Grit Chambers 

Number of units 2 3 

Unit length, ft 51 51 

Unit width, ft 18 18 

Unit depth, ft 12 12 
Overflow rate, gpd/sq ft 

Average day 16, 800 16,500 

Peak 41,200 36,700 
Detention time, min 

Peak 3.1 3.5 

Primary Tanks 

Number of units 4 5 

Type Circular Circular 

Diameter, ft 110 110 
Overflow rate, gpd/sq ft 

Average day 815 960 

Peak 1,990 2,125 

Aeration Tanks 



BODc, lb/day^ 1 ' 








Average day 




43,050 


55,240 


Peak 




86,100 


131,000 


Number of units 




4 


6 


Unit length, ft 




240 


240 


Unit width, ft 




60 


60 


Unit depth, ft 




15 


15 


Loading, lb of BOD^/l, 
Average 


000 cf 








50 


43 


Peak 




99.6 


101 


Secondary Settling Tanks 








Flow, mgd 








Average day 




31 


45.6 


Peak 




75.6 


101 


Number of units 




6 


8 


Type 




Circular 


Circular 


Diameter, ft 




120 


120 


Overflow rate, gpd/sq 


ft 






Average day 




460 


500 


Peak 




1,120 


1,120 



3-8 



TABLE 3-3 (Continued). BASIC DESIGN CRITERIA - MIDDLE 
CHARLES RIVER ADVANCED WASTEWATER TREATMENT PLANT 

2000 design 2050 

Nitrification Reactors 



NHo-N load, lb/day 
Average 












5,430 




7,990 


Number of units 




4 




6 


Unit length, ft 




212 




212 


Unit width, ft 




53 




53 


Unit depth, ft 




15 




15 


Nitrification Settling 


Tanks 








Flow, mgd 










Average day 




31 




45.6 


Peak 




73. 


6 


101 


Number of units 









8 


Type 




Circular 


Circular 


Diameter, ft 




125 




125 


Overflow rate, gpd/sq 


ft 








Average 




420 




465 


Peak 




1,025 




1,030 


Multi-Media Filters 











Number of units 6 8 

Unit length, ft 36 36 

Unit width, ft 36 36 
Filtration rate, gpm/sq ft 

Average day 2.8 3.1 

Chlorine Contact Chambers 

Flow, mgd 

Average day 31 45.6 

Peak 75.6 101 

Number of units 2 2 

Unit length, ft 100 100 

Unit width, ft 35 48 

Unit depth, ft 15 15 
Detention time, min 

Average day 36.5 34.1 

Peak 15 15.4 

1. Includes recycle load. 



3-9 



retention at peak flow. To meet this particular design 
criteria, two units would be constructed at each plant. 
The grit that accumulates within the units would be period- 
ically removed by an overhead clam bucket. The grit could 
be disposed of either by landfill or by incineration. 

Some of the pollutant load, particularly SS, is 
precipitated in the primary treatment process. The effi- 
ciency of the process is inversely related to the design 
overflow rate. As indicated in Tables 3-2 and 3-3> design 
overflow rates range from 7^0 to 815 at average flow condi- 
tions, and from 1980 to 1990 at peak flow conditions. These 
overflow rates will insure proper operation of the primary 
treatment process. To achieve these overflow rates, six 
85-foot diameter circular primary tanks would be required 
at the Upper Neponset River plant, and four 110- foot diam- 
eter tanks at the Middle Charles River plant. Sludge 
removed from the process could be vacuum filtered to 
increase its solids content and then could be incinerated. 
Other alternatives are discussed later on. 

The effluent from the primary tanks would be 
discharged to aeration tanks. In the aeration tanks, a 
biological mass would be maintained to further reduce the 
pollutants, particularly BOD5, in the wastewater. For 
preliminary sizing of the aeration tanks, we have conser- 
vatively assumed that the step aeration activated-sludge 
process would be appropriate for this treatment train. To 
be within the range of acceptable BOD5 loadings for this 
process, four aeration tanks will be required at each plant. 
The dimensions of these tanks are shown in Tables 3-2 and 
3-3 for the Upper Neponset and Middle Charles plans, 
respectively. The aeration tanks have been so arranged 
that mechanical aerators may be used to supply oxygen to 
the biological mass in the aeration tanks. This was done 
because our previous studies for similar plants indicate 
that mechanical aeration is the more economical means of 
furnishing oxygen for plants of these capacities. 

The secondary treatment process includes not only 
the aeration tanks but also the final settling tanks. In 
these tanks, the biological mass that is carried over 
from the aeration tanks is separated from the effluent. 
Some of this separated activated sludge is wasted to main- 
tain equilibrium conditions in the aeration process. The 
wasted activated sludge may be thickened, vacuum filtered 
and incinerated. As shown in Tables 3-2 and 3-3, six 
circular final settling tanks of the dimensions indicated 
would be required at each plant. As in the case of the 



3-10 



primary settling tanks, these facilities have been sized to 
provide adequate overflow rates to insure good solids 
separation. Phosphorus removal will be achieved in the 
secondary (activated sludge) system by precipitation with 
metal salts and removal of the precipitate. This is a 
chemical-biological process and requires no major facilities 
beyond those normally required for Secondary Treatment. 
However, chemical handling facilities would be required and 
there would be an increased load imposed on the sludge 
handling facilities due to the increased volume of sludge. 

The nitrification unit process consists of nitrifi- 
cation reactors and nitrification settling tanks. The 
nitrification unit process is a biological process similar 
in concept to the previously described secondary treatment 
unit process. 

Experience indicates that the biological rate of 
nitrification can materially vary for different wastewaters 
which effects the sizing of the reactors. For this reason, 
the nitrification process should be piloted before actual 
design parameters are selected. Four reactors of the 
dimensions shown in Tables 3-2 and 3-3 would be required at 
each site. The nitrification reactors have been so arranged 
that mechanical aerators may be used to furnish an oxygen 
supply to the biological mass in the aeration tanks. 

Six nitrification settling tanks would be required 
at each site to provide acceptable overflow rates. Since 
the rate of growth of the biological mass in the nitrifica- 
tion reactors is not appreciable, a large quantity of 
sludge need not be wasted to maintain equilibrium condi- 
tions in the nitrification process. That sludge which is 
wasted may be handled in the same manner as previously 
described for waste activated sludge. 

To further refine the quality of the effluent, six 
multi-media filters would be provided at each plant. 
Experience has indicated that these filter units have more 
consistent and higher removals if operated at a constant 
flow rate over a 24-hour period. Since the incoming waste- 
waters would have a diurnal flow variation, flow equaliza- 
tion basins are provided ahead of the filtration units. 
These basins are designed to smooth out the diurnal varia- 
tion by having the capacity to store ircoming wastewaters 
during times of daily peak flow. The stored wastewater 
would be discharged to the filters durjng periods of minimum 
incoming flow. A conservative uniform filtration rate of 
approximately 3 gpm (gallons per minute ) per square foot 
per day based on the average daily flow has been used in 
selecting the number and size of the filtration units. 

3-11 



Present effluent standards require that the effluent 
be disinfected to reduce total coliform levels in accor- 
dance with the requirements of the stream standards as 
established by the regulatory agencies. In the case of the 
use of chlorine for disinfection this will normally require 
a residual concentration of 1.0 mg/L after a 15 minute 
retention period. For this purpose, each plant has been 
provided with chlorine contact chambers of sufficient 
dimensions to provide the necessary retention time at 
peak flow. 

Postaeration is a relatively new requirement for 
wastewater treatment plants. Experience indicates that 
mechanical aerators or diffused air, placed in the chlorine 
contact chambers, will provide adequate postaeration 
without effecting the disinfection process. For this 
reason, no additional facilities are indicated for post- 
aeration of the final effluent. 

Site Layouts 

Preliminary site layouts for the Upper Neponset 
River and Middle Charles River wastewater treatment plants 
are shown on Figures 3-2 and 3-3, respectively. These site 
layouts are not site specific and are presented to indicate 
a general arrangement of the various process units. 

It is uncertain whether or not the incoming sewer 
will be at such an elevation in relation to the site topo- 
graphy to permit gravity flow through the treatment plant. 
For this reason, and as it is usually required, an influent 
pumping station is shown at each site. The pumping units 
would be designed to lift the incoming wastewaters to such 
an elevation that flow from the aerated grit chambers 
through the primary, secondary and nitrification process 
and to the equalization basins would be by gravity. A 
second pumping station would be required to lift wastewater 
from the equalization basin to the multi-media filters. 
It is anticipated that the multi-media filters could be 
placed at such an elevation that discharge from them through 
the chlorine contact chambers to the receiving stream 
could be by gravity. For this reason, no effluent pumping 
station is indicated. 

The influent pumping station would be equipped with 
comminutors. The function of this equipment is to grind 
up any large solids that might interfere with the operation 
of the pumps. 

The site would have sufficient space to provide for 
a chlorine building, a sludge process building and an 

3-12 



NITRIFICATION SETTLING TANKS 




PUMPING STATION 



V 



7 

L— nisiNF 



•a OOOOO 1 
OOOCr 



AERATION TANKS 
PRIMARY SETTLING TANKS 



MULTI-MEDIA FILTERS 



SLUDGE 

PROCESS 

BLDG. 



CHLORINE BLDG. 



V 



AERATED 

GRIT 

CHAMBERS- 



DISINFECTION 



LEGEND 



a 



ADMINISTRATION 

AND OPERATIONS BLDG. A 

INFLUENT 
PUMPING STATION 
ANDCOMMINUTORS 



1ST PHASE DEVELOPMENT 
2ND PHASE DEVELOPMENT 



FIG. 3 2 UPPER NEPONSET RIVER WWTP LAYOUT 



NITRIFICATION SETTLING TANKS 




PUMPING STATION 



r^MULTI-MEDIA 
- J FILTERS 



PRIMARY SETTLING TANKS' 



T D 



| BLDG 
I 
J 

ISINFECTION 



3INE 




SLUDGE 

PROCESS 

BLDG. 





B' 



-AERATED 
GRIT 
CHAMBERS 



L 



ADMINISTRATION 

AND OPERATIONS BLDG. 



"" U— INF 
PUI\ 



LUENT 
PUMPING STATION 
ANDCOMMINUTORS 



LEGEND 
1ST PHASE DEVELOPMENT 



2ND PHASE DEVELOPMENT 



FIG. 3 3 MIDDLE CHARLES RIVER WWTP LAYOUT 



administrative and operations building, along with space 
for additional facilities projected for the future year 
2050 flows. 

The chlorine building would house the chlorination 
equipment and be designed to accept chlorine shipments in 
tank truck lots. 

The sludge process building would house the sludge- 
flotation thickeners, the vacuum filters, and incinerators. 
The incinerators would be of the multiple-hearth type and 
would be furnished with such appurtenant equipment to 
insure a stack discharge complying with regulatory agency 
standards. 

The preliminary layouts indicate that the Upper 
Neponset and Middle Charles treatment plants would require 
27 and 32 acres, respectively to accommodate the plant 
facilities themselves. The appropriate buffer zone require- 
ments, which depend on the adjacent land use, would be 
required over and above the previously cited acreage 
requirements. 

Costs 

General . Estimated construction and operating and 
maintenance costs for the Upper Neponset River and Middle 
Charles River wastewater treatment plants are presented in 
this section. 

The estimated construction costs are based on 1975 
dollars (ENR Index of 2200) and include a 35 percent 
allowance for engineering and contingencies. Costs do not 
include the cost of land, right-of-ways, legal fees nor 
financing during construction. 

Construction Costs . The construction cost for the 
Upper Neponset River and the Middle Charles River waste- 
water treatment plants are presented in Tables 3-^ and 3-5, 
respectively, and were estimated by segregating major compo- 
nents of the plant and listing them on an individual basis. 

These costs do not allow for any extraordinary site 
development cost such as the cost for pile construction, 
dyking or removal of large quantities of unsuitable foun- 
dation materials. 

Operation and Maintenance Costs . Annual operating 
and maintenance costs for the Upper Neponset Wastewater 
Treatment Plant have been estimated for 1990 and 2000. 
These estimated costs are presented in Table 3-6. A similar 
presentation is made for the Middle Charles Wastewater 
Treatment Plant in Table 3-7. 

3-15 



TABLE 3-4. CONSTRUCTION COST^ - UPPER NEPONSET 
RIVER WASTEWATER TREATMENT PLANT 

Item Cost, $ 

Influent pumping station 1,394,000 

Aerated grit chambers 801,000 

Primary settling tanks 1,544,000 

Aeration tanks 4,756,000 

Final settling tanks 2,737,000 
Returned sludge and waste activated-sludge 

pumping station 2,367,000 

Nitrification reactors 2,660,000 

Nitrification settling tanks 3,067,000 
Nitrification returned sludge and waste 

activated-sludge pumping station 1,788,000 

Intermediate pumping station 551,000 

Equalization basin' 257,000 

Multi-media filters 1,582,000 

Chlorine contact chambers 1,244,000 

Sludge processing building 8,308,000 

Administration and maintenance building 601,000 

Outside piping and landscaping 3,370,000 

Electrical and instrumentation 4, 073, 000 

Total 41,100,000 

IT Based on 1975 dollars at ENR 2200. 



Manpower costs are based on current Metropolitan 
District Commission wage rates and include fringe benefits. 
Fuel costs are computed at a unit price of 35.6 cents per 
gallon and power costs at a unit price of 3 cents per kwh. 
Chlorine, ferric chloride, alum and lime costs are predi- 
cated on a purchase price of 205, 190, 70, and 51 dollars 
per ton, respectively. Maintenance expenditures are taken 
to be equal to 1 percent of the cost of mechanical equip- 
ment, plus one half a percent of the cost of buildings and 
other permanent structures. 

Sludge Management Techniques 

General . Sludge generated at wastewater treatment 
plants depending on plant capacity and on local factors may 
be disposed of in various ways. Because of the urban loca- 
tion of the satellite plants, the more desirable alterna- 
tives from an economic and environmental impact standpoint 
may prove to be disposal by incineration, disposal in land- 
fill and disposal with solid refuse waste. Land application 
of sludges has proven to be an acceptable method of disposal 

3-16 



where the sludge has been stabilized, contains no toxic 
metals, and where areas of sufficient acreage having proper 
soil, groundwater, and crop coverage characteristics have 
been available. Since the identification of such sites 
is beyond the scope of this study, land application was 
not considered further in this investigation. 

TABLE 3-5. CONSTRUCTION COST^ - MIDDLE CHARLES 
RIVER WASTEWATER TREATMENT PLANT 

Item Cost, f~ 

Influent pumping station 1,825,000 

Aerated grit chambers 987,000 

Primary settling tanks 1,852,000 

Aeration tanks 5,852,000 

Pinal settling tanks 3,218,000 
Returned sludge and waste activated-sludge 

pumping station 2,600,000 

Nitrification reactors 3,302,000 

Nitrification settling tanks 3,740,000 
Nitrification returned sludge and waste 

activated-sludge pumping station 2,195,000 

Intermediate pumping station 674,000 

Equalization basin 316,000 

Multi-media filters 1,945,000 

Chlorine contact chambers 1,532,000 

Sludge processing building 10,217,000 

Administration and maintenance building 732,000 

Outside piping and landscaping 4,107,000 

Electrical and instrumentation 4 , 506, 000 

Total 49,600,000 

T. Based on 1975 dollars at ENR 2200. 



For the purposes of site layout and costing, sludge 
disposal by incineration has been selected for the Upper 
Neponset River and Middle Charles River wastewater treat- 
ment plants. This selection has been made for comparative 
purposes only. Before final design is undertaken, the 
sludge management technique to be used at these plants 
should be reviewed and should include landfill disposal, 
disposal with solid refuse wastes as well as incineration. 

Sludge Quantities . Table 3-8 presents the estimated 
quantities of sludge that would be generated in 1990 and 
2000 at the Upper Neponset River and Middle Charles River 
wastewater treatment plants. 

3-17 



TABLE 3-6. ANNUAL OPERATION AND MAINTENANCE COST^ - 
UPPER NEPONSET RIVER WASTEWATER TREATMENT PLANT 

Item 1990, $/yr 2000, $/yr 

Manpower 

Operation and maintenance 725,000 790,000 

Fuel and Electric Power 

Fuel 17,000 17,000 

Electric power 735,000 9^8,000 

Chemical 

Chlorine 32,000 39,000 

Ferric chloride 77,000 84,000 

Alum 440,000 533,000 

Lime 62,000 67,000 

Maintenance 

Plant 172,000 172,000 

Total 2,260,000 2,650,000 

T~. All costs are in 1975 dollars. 



TABLE 3-7. ANNUAL OPERATION AND MAINTENANCE COST^ - 
MIDDLE CHARLES RIVER WASTEWATER TREATMENT PLANT 

Item 1990, $/yr 2000, $/yr 



Manpower 

Operation and maintenance 790,000 880,000 

Fuel and Electric Power 

Fuel 18,000 18,000 

Electric power 948,000 1,105,000 

Chemical 

Chlorine 39,000 48,000 

Ferric chloride 84,000 104,000 

Alum 536,000 664,000 

Lime 67,000 84,000 

Maintenance 

Plant 207,000 207,000 

Total 2,689,000 3,110,000 

"H All costs are in 1975 dollars. 

3-18 



TABLE 3-8. SLUDGE QUANTITIES 



Quantity unit Upper Neponset Middle Charles Total 



1990 

Tons/yr (dry) 
Tons/yr (wet) 
Cy/yr (wet) 
Cy/yr (ash) 

2000 

Tons/yr (dry) 
Tons/yr (wet) 
Cy/yr (wet) 
Cy/yr (ash) 



8,400 
36,500 
38,620 

9,950 

10,400 
45,260 
47,880 
12,860 



10,770 
46,820 
49,530 
13,220 

13,140 
57,130 
60,460 
16,100 



' 19,170 
83,320 
88,150 
23,170 

23,540 
102,390 
108,340 

28,960 



Sludge quantities are given in terms of tons per year 
dry, tons per year wet, cubic yards per year wet, and cubic 
yards per year as ash. 

Wet-sludge quantities are based on a 23 percent 
solids and a 77 percent moisture content. These charac- 
teristics are typical of sludge cake as produced by the 
vacuum filtration process. 

Ash quantities are based on the residue that would 
remain after incineration of the sludge. 

Incineration . Incineration would be accomplished 
through the use of multiple-hearth incinerators. This 
method of sludge disposal is successful and is currently 
used at many treatment plants in the United States. 

Incinerators designed for sludge disposal are not 
the same as the open grate incinerator commonly used for 
burning municipal refuse. The refuse incinerator is not 
well adapted for disposal of vacuum-filtered sludge because 
of the high moisture content of the cake. 



3-19 



The multiple-hearth incinerator is a refractory 
brick-lined steel shell in which a number of intermediate 
horizontal hearths are placed. Each hearth is provided 
with central or peripheral drop holes through which the 
sludge may pass downward through the furnace. At each 
hearth level, a number of rabble arms are driven by a 
central rotating shaft. The function of the rabble arms is 
to continuously turn over and agitate the sludge and to 
convey the burning material across the hearth. The sludge 
cake from the vacuum filters is loaded at the top of the 
incinerator and is carried through the incinerator by the 
rabble arms from hearth to hearth. At the bottom of the 
incinerator, the ash is removed, either by hydraulic or 
mechanical means. 

The combustion process is normally self-supporting 
when handling sludges derived from municipal wastes except 
for the period of startup. However, for safety and to 
insure good combustion, some of the burners are kept at a 
low fire setting during the combustion process. 

Air for the combustion process is furnished by a 
variable-speed, induced-draft fan that can be regulated to 
meet combustion requirements. Hot gases are withdrawn 
at the top of the furnace so that the flow of heated air 
is counter current to the flow of sludge. Particulates, 
aerosols and smoke are removed from the hot gases through 
the use of a venturi or multi-stage impingement-type 
scrubber. With these devices, 90 to 95 percent of all 
particulates can be removed. 

The multiple-hearth furnace has been very successful 
in handling sewage sludges because it can process lumpy 
material, can evaporate large quantities of water, and 
provides good exposure of the sludge to the combustion air. 

Table 3-8 indicates that if the sludge is incinerated, 
12,860 and 16,100 cubic yards of ash would be produced each 
year at the Upper Neponset River and Middle Charles River 
plants, respectively. If the ash from each plant is disposed 
of in landfill to a 20- foot depth, approximately 0.5 acres 
per year of fill area would be needed. This is not an 
excessive acreage requirement and such a site may well be 
available within a reasonable haul distance from each plant 
site. 

It is acceptable to dispose of ash together with the 
solid waste refuse in a sanitary landfill. In such an 
operation, the ash would be mixed with solid waste refuse, 
deposited in approximately 8-foot lifts, and covered with 
a clean soil material. 

3-20 



The advantages of incineration can be attributed to 
the nature and quantity of the final disposal product. The 
ash is inert, sterile and has a low potential for pollution. 
This sludge management technique produces on a relative 
basis, the smallest quantity of material requiring final 
disposal. Accordingly, landfill acreage requirements are 
minimal. 

The disadvantage is that incineration can be the 
most costly sludge management technique. 

Landfill . Sanitary landfill of vacuum-filtered 
sludge is an acceptable method of disposal. The filtered 
sludge must be limed and covered with a quantity of clean 
fill material that about equals the quantity of deposited 
sludge. For this reason and because the quantity to be 
disposed of is much larger, acreage requirements are higher. 
We estimate that by 2000, yearly acreage requirements would 
be approximately 3 acres for the Upper lleponset plant and 
3.7 acres for the Middle Charles River plant based on a 
total depth of 20 feet including the required cover material. 

Sanitary landfill sites must be carefully selected 
and operated so that the underground water is not contami- 
nated and so that there is no direct seepage from the fill 
area. Where direct seepage from the fill area is encoun- 
tered, the leachate must be collected and returned to a 
sewer system for treatment or treated on site. Since this 
is costly, impervious cover materials are usually used to 
prevent the influx of rainfall into the disposal site and 
the site is properly graded to permit any rainfall to run 
off to adjacent lands. Because impervious cover material 
may not be available on site, it may have to be hauled in 
which adds appreciably to the cost of the operation. 

The major advantage of the method given a proper 
site of sufficient acreage within a reasonable haul 
distance from the plant is that it is usually much more 
economical than disposal by incineration. The disadvan- 
tages are the large site requirements, the potential for 
pollution, and the requirement of large quantities of 
cover material. 

Proper site selection for sanitary landfill of 
filtered sludge requires a detailed engineering analysis 
and was not considered to be within the scope of this 
study. 



5-21 



Disposal with Refuse . A report on the disposal of 
municipal solid waste within the State* was undertaken for 
the Massachusetts Department of Public Works. This report 
indicates that it would be beneficial and economical to 
implement a municipal solid waste management system (MSW) 
and to market the recycled materials. A beneficiated frac- 
tion (BCF)** would be produced from the solid wastes and 
sold as a fuel. Since the time of the report, actual bid 
prices for BCF have increased over threefold due to the 
increase in fuel prices. This increase implies that a 
greater economic benefit could be realized from the recy- 
cling of solid waste. 

The report suggests that a primary resource recovery 
plant should be located in the vicinity of the Massachusetts 
Turnpike and Route 128. The function of the primary 
resource recovery plant would be to separate recyclable 
materials and to produce the BCF. This proposed location 
is within a reasonable haul distance from potential waste- 
water treatment plant site locations along the Upper 
Neponset River and Middle Charles River. 

Our preliminary studies indicate that sludge cake 
produced by vacuum filtration could be hauled to and 
processed at a primary resource recovery plant. It would 
be necessary to reduce the moisture content of the incoming 
sludge cake from 77 to approximately 23 percent so that 
the sludge cake would have a moisture content consistent 
with the incoming solid waste. To do this, additional 
drying capacity would be required at the recovery plant. 
Part of the beneficiated fraction produced at the plant 
would be used as fuel for the drying process. 

A cost for utilizing this method of disposal would 
be incurred for hauling sludge and for constructing and 
operating the primary resource recovery plant on a propor- 
tionate load basis. This cost may be offset by the savings 
that would be realized by eliminating incineration facili- 
ties at both plants and the value of the BCF produced. 



*A Systems Evaluation of Alternative Statewide Resource 
Recovery Techniques for the Disposal of Municipal Solid 
Waste, Arthur D. Little, Inc., December 1973. 
**BCF or Beneficiated Combustible Fraction - A fraction of 
the MSW stream formed by removing some or all of the 
noncombustibies , some or all of the moisture, and shred-, 
ding to a specified nominal size. 



3-22 



An Investigation as to the economics of this method 
of disposal is beyond the scope of this study. However, if 
a solid waste recycle program is initiated in the near 
future, the potential for disposing of sludge produced at 
the satellite plants in conjunction with solid wastes 
should be investigated. 



3-23 



CHAPTER 4 

INTERCEPTOR, PUMPING STATION AND 
HEADWORKS IMPROVEMENTS 



Genera l 

The purpose of this chapter is to discuss the MDC 
interceptors., pumping stations and headworks in terms of 
their adequacy to meet projected needs under the recommended 
plan. Specific details relating to these topics are 
presented in Technical Data Vol. 9, MDC Interceptor and 
Pumping Stations A nalysis and Improvements . 

E xisting System 

The MDC sewerage system 3 called the MSD, includes 
treatment plants at Deer Island and Nut Island in the 
Boston Harbor serving respectively the North Metropolitan 
and South Metropolitan sewerage systems covering areas 
generally shown on Figure 4-1, Four headworks, 12 pumping 
stations and interceptors totalling 225 miles presently 
serve 42 communities including the City of Boston. The MSD 
has 43 member communities, all of which contribute flow 
except for Hoibrook. Also, the MSD presently operates 
combined sewer overflow control facilities in Cambridge and 
Somerville. These, however, are discussed in Technical 
Data Vol. 7, Combi ned Sew e r Overflow Regu l ation . 

The total area and population served by the MSD is 
presently 132,800 acres and 1,970,300, respectively. The 
system, which serves 43 communities at present, is divided 
into the North Metropolitan Sewerage System and the South 
Metropolitan Sewerage System. 

North Metropolitan Sewerage System 

About 68,200 acres and about 1,340,200 persons plus 
nondomestic contributions are served by the Deer Island 
Treatment Plant. This includes 22 communities plus parts 
of Boston, Brookline, Milton, and Newton, Table 4-1 
summarizes the communities, population and areas served 
by this system. 

Seven of the 12 total MDC pumping stations are in 
the North Metropolitan system. These are the Alewife 
Brook, Charlestown, East Boston Electric, East Boston 
Steam and Reading.' The Old Deer Island and Winthrcp pump- 
ing stations are in existence but are no longer in active 



4-1 




FIG. 4-1 AREAS SERVED BY THE EXISTING METROPOLITAN INTERCEPTOR 
SYSTEMS AND THE DEER AND NUT ISLAND WASTEWATER TREATMENT PLANTS 



use. The Deer Island Pumping Station is being phased out 
of the system now that flows are being diverted directly 
to the Winthrop Terminal facility. Flows tributary to the 
Winthrop Pumping Station now enter the MDC North Metropol- 
itan Sewer by gravity since most of the flows tributary to 
this sewer have been diverted to the North Metropolitan 
Relief Tunnel. 



TABLE 4-1. EXISTING NORTH METROPOLITAN SEWERAGE 
SYSTEM (DEER ISLAND) SERVICE AREA 



Number 



Community 



Name 



Sewered 
population 



Sewered 
acres 



2 
5 
7 
15 
17 
18 
22 
30 

43 

48 

55 
57 
61 
66 
77 
78 
86 
88 
95 
97 
98 
107 
108 

109 
110 
112 

113 

114 

115 
117 
118 
123 
124 



Arlington 

Bedford 

Belmont 

3rookline (part) 

Burlington 

Cambridge 

Chelsea 

Everett 

Lexington 

Maiden 

Medford 

Melrose 

Milton (part) 

Newton (part) 

Reading 

Revere 

Somerville 

Stoneham 

Wakefield 

Walt ham 

Watertown 

Wilmington 

Winchester 

Winthrop 

Woburn 

Boston Proper - 
Brighton 
Charlestown 
Dorchester 
East Boston 
PNWY-JMACA 
Roxbury 
South Boston 

Total 



53 


,600 


6 


,100 


24 


,400 


30 


,700 


10 


,800 


100 


,400 


30 


,600 


42 


,500 


24 


,600 


56 


,100 


63 


,800 


33 


,200 


4 


,900 


41 


,100 


13 


,500 


40 


,600 


88 


,700 


19 


,700 


22 


,400 


46 


,200 


39 


,300 




200 


22 


,300 


20 


,300 


27 


,700 


67 


,100 


63. 


,600 


15. 


,400 


1 .2 


,100 


;8 


,800 


,8 


,300 


18 


,200 


i3 


,100 



3 


,000 


1 


,400 


2 


,000 




860 


3 


.900 


3 


,400 


1 


,000 


1 


,300 


4 


,400 


2 


,600 


2 


,750 


2 


,000 




230 


4 


,120 


2 


,100 


1 


,800 


2 


,300 


1 


,900 


2 


,250 


4 


,300 


2 


,100 




50 


2 


,550 




800 


2 


,100 


1 


,480 


1 


,990 




480 


2 


,900 


1 


,120 


1 


,290 


2. 


,290 


1 


47C 



1,3 >0,200 



68,230 



4-3 



All four headworks, namely Chelsea Creek, Columbus 
Park, Ward Street, and Winthrop Terminal facility are also 
part of the North Metropolitan Sewerage .System. 

South Metropolitan Sewerage System 

An estimated 64,600 acres are sewered in the area 
tributary to this system serving atout 630,200 persons, 
plus nonresidential contributors. 

Wastewater from 16 communities plus parts of Boston, 
Brookline, Milton, and Newton flows to the Nut Island 
Treatment Plant as shown in Table 4-2. 

The remaining five pumping stations of the MSD are 
the Braintree-Weymouth, Hingham, Quincy, Houghs Neck and 
Squantum pumping stations. 

Interceptor Relief Requirements 

The Recommended Plan visualizes the addition of the 
Town of Lincoln, Lynnfield and Weston to the North Metro- 
politan System and Dover, Hopkinton, Sharon, Sherborn, and 
Southborough to the South Metropolitan System. In addition, 
as discussed in Chapter 3, two new satellite wastewater 
treatment plants are proposed for the South Metropolitan 
System - discharging to the Middle Charles and Upper 
Neponset Rivers. The proposed Middle Charles Treatment 
Plant would serve Ashland, Framingham, Hopkinton, Natick, 
Sherborn, and Southborough and parts of Dover and Wellesley. 
The proposed Upper Neponset Treatment Plant would treat 
wastewater from Sharon, Stoughton and Walpole and parts of 
Canton and Norwood. Under this Recommended Plan, areas 
served by the four treatment plants would be as follows: 

Deer Island Treatment From present 68,200 to 
Plant 87,600 sewered acres in 

year 2000 

Nut Island Treatment From present 64,600 to 
Plant 58,000 sewered acres in 

year 2000 

Proposed Middle Charles 24,100 sewered acres In 
Plant year 2000 

Proposed Upper Neponset 17,200 sewered acres in 
Plant year 2000 



4-4 



TABLE 4-2. EXISTING SOUTH METROPOLITAN SEWERAGE 
SYSTEM (NUT ISLAND) SERVICE AREA 





Community 


Sewered 
population 


Sewerod 


Number 


Name 


acres 


3 


Ashland 


1,100 


250 


14 


Braintree 


34,400 


4,400 


16 


Brookline (part) 


27,500 


2,330 


19 


Canton 


8,900 


1,650 


26 


Dedham 


23,800 


2,700 


31 


Framlngham 


50,600 


7,000 


36 


Hingham 


3,800 


650 


37 


Holbrook(l) 








62 


Milton (part) 


20,700 


2,510 


64 


Natick 


21,400 


3,800 


65 


Needham 


25,500 


3,600 


67 


Newton (part) 


50,000' 


6,260 


72 


Norwood 


30,500 


3,200 


75 


Quincy 


88,000 


5,250 


76 


Randolph 


13,500 


1,800 


89 


Stoughton 


5,600 


1,000 


96 


Walpole 


5,800 


1,100 


100 


Wellesley 


22,700 


6,200 


105 


Westwood 


4,300 


600 


106 


Weymouth 
Boston 


27,800 


3,050 


116 


Dorchester 


25,700 


410 


119 


FNWY-JMACA 


10,000 


490 


120 


Hyde Park 


38,300 


2,^ 


121 


Mattapan(2) 


37,200 


96 


122 


Roslindale(2) 


23,200 


1,3 


125 


West Roxbury 

Total 


25,000 


v 




630,200 


64,6; ' 



1. Presently not served by the MDC. 

2. Negligible areas of Mattapan and Roslindaie that c 
tribute to the Deer Island Treatment Plant are cons.' 
ered tributary to the Nut Island Treatment Plant. 



MDO interceptors requiring relief under the F 3 
mended Plan are shown on Figure 4-2 (bound in back] . 
extent and size of pipes to be relieved are shown in 
Table 4-3 along with the estimated time when such relief 
would be required. 



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Relief sizes shown in Table 4-3 are based on the 
assumption that such relief would be constructed parallel 
to existing pipes. In final design, other more appropriate 
alignments and slopes may be selected. For this reason, 
the design flows for each sewer to be relieved is presented 
in Table 4-4. 

The estimated cost of interceptor relief in accor- 
dance with the groupings of pipes presented in Table 4-3 
is shown in Table 4-5. 

Under the Recommended Plan, extension of intercep- 
tors will be required to serve expected new member commun- 
ities. The estimated size, length and cost of these is 
shown in Table 4-6 along with the projected date when such 
facilities will be needed. 

Wastewater Pumping Station Analysis and Improvements 

This section discusses the following 10 existing 
pumping stations. Their approximate location is shown on 
Figure 4-2 (bound in back) : 

Alewife Brook Hingham 

Braintree-Weymouth Houghs Neck 

Charlestown Quincy 

East Boston Steam Reading 

East Boston Electric Squantum 

The remaining two, namely the Old Deer Island and 
Winthrop pumping stations, are not discussed in this 
section due to their status of not being used. 

Capacity Requirements . Table 4-7 sets forth the 
total installed capacity, the present available capacity 
and the year 2000 capacity requirements for each of the 10 
pumping stations evaluated. The future capacity require- 
ments are based on estimated year 2000 dry-weather flows. 
Those stations serving combined sewer areas must be further 
evaluated for capacity needs as part of detailed combined 
sewer overflow regulation analysis in their areas and all 
pumping station capacities must be further studied during 
infiltration/inflow analyses. 

The available capacity is reported to be limited in 
some cases by excessive head losses caused by the force 
mains and/or the arrangement of the discharge piping within 
the station. Such conditions are said to exist at the 
Braintree-Weymouth, East Boston Steam, Quincy and Reading 



4-11 





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4-16 



TABLE 4-5. ESTIMATED COST OF INTERCEPTOR IMPROVEMENT 

REQUIRED UNDER THE RECOMMENDED PLAN 

Name of interceptor' Esi imated cosl , 

No.O) requiring relief (millions of dollars) 

1 Millbrook Valley Sewer 3.8 

2 Wilmington Extension 

Sewer 3.0 

3 Reading Extension 

Sewer On-going 

4 North Metropolitan 

Sewer 1.7 

5 Chelsea Branch Sewer 0.1 

6 Revere Extension Sewer 3-4 

7 Stoneham Extension 

Sewer 0.3 

8 Stoneham Trunk Sewer 0.1 

9 Wakefield Branch Sewer 1.0 

10 Wakefield Trunk Sewer 4.8 

11 North Charles 

Metropolitan Sewer 1.3 

12 South Charles Relief 

Sewer 2.7 

13 South Charles Relief 

Sewer 2.9 

14 South Charles River 

Sewer 12.6 

15 Charles River Crossing Included in No. 14 

16 Cross Connection Included in No. 14 

17 Cummingsville Brand 

Sewer 1.0 

18 Somerville-Medford 

Branch Sewer 4.5 

Subtotal North System 4^.2 

19 Upper Neponset Valley 

Sewer On-going 

20 New Neponset Valley 

Sewer Included in No. 21 

21 Stoughton Extension 

Sewer 1.9 

22 Walpole Extension 

Sewer 11.9 

23 Westwood Extension 

Sewer 2 . 4 

24 Braintree-Weymouth 

Extension Sewer 0.9 

25 Framingham Extension 

Sewer 22 .5 

Subtotal South System 39.6 

Tot a; North and South Systems 82.8 

1. Numbers correspond to 'hose in Table 5-1. 

4-17 



pumping stations. Since at times of maximum inflow the 
Braintree-Weymouth, Quincy and Reading stations must regu- 
late the incoming flow, it would seem prudent, where 
detailed hydraulic studies so indicate, to relieve this 
operational condition by providing additional force main 
capacity. In any event, this additional capacity will be 
required for year 2000 flows and any additional capacity 
can be utilized whether or not the particular pumping 
station is replaced with a new facility or retained. 



TABLE 4-6. INTERCEPTOR REQUIREMENTS FOR NEW 
COMMUNITIES UNDER THE RECOMMENDED PLAN 

Interceptor designation Size, in. Length, ft Cost, $"" 

Lynnfield extension sewer Varies 6,000 367,000 

12 to 21 

Ashland-Hopkinton exten- Varies 36,700 4,459,000 
sion sewer 21 to 48 

Weston-Lincoln extension Varies 33,400 3,832,000 
sewer 30 to 42 

Southborough extension Varies 26,800 2,421,000 
sewer 24 to 36 

Sharon extension sewer 36 7,400 1,218,000 

Total 12,297,000 



Summary of Improvements Needed . The normal life of 
a pumping station structure by today f s engineering design 
standards is usually limited to 50 years, while the life of 
prime movers and pumping units is limited to 15 to 20 years. 
Using these criteria, many of the existing structures, 
prime movers and pumping units hav served their useful 
life. That this is actually so in most cases is borne out 
by the rehabilitation needs noted in Table 6-2 of Technical 
Data Vol. 9, and the presently experienced difficulty in 
securing replacement parts for some of the older operating 
units. The information presented is derived from field 
inspections and discussions with supervisory and operating 
personnel. 



4-18 



TABLE 4-7- FUTURE CAPACITY REQUIREMENTS FOR DRY WEATHER PLOWS - 2000 

Installed 

capacity 2000 capacity 

largest requirements 

Total unit Estimated Average Peak 

Installed out of available dry dry Type of 

capacity, service, capacity, weather, weather, area 

Pumping station mgd mgd mgd mgd mgd served Remarks 

Alewife Brook 90.6 6U.4 90. b 13.7 



30.9 


Combined-: 




separate 


58.7 


Separate 



Braintree-Weymcuth 60 40 44(D 26.9 58.7 Separate Increased pump- 
ing capacity tc 



60 mgd with 
largest unit 



73. 


5 


separate 




20. 





Combined 
Combined 


tipr.al sr.aller 
capacity p ;-.;-- 
ing units tc 
handle cry 
weather flows. 


8. 


3 


.Separate 


Increase ;- uliliy- 



Charlestown 140 90 l4o 33-3 
East Boston Steam 205(3) 105 135-150^2) a. 8 



East Boston Electric 125 50 125 Standby 

rtlngnam '4,2 2.i> $.5 <? • 5 

ing capacity tc 
9 mgd with 
largest unit 
out cf service. 

Houghs Neck 2.8 1.4 - 1.2 2.2 Separate Increase pump- 

ing capacity tc 
3 mgd with 
largest unit 
cut of service. 

Quincy 

Reading 



oquanturn 
Total 



52 


32 


20.0(2) 


14.5 


26.2 


Separate 


« 


4 


4.0(2) 


4.9 


14. C 


Separate 





4 


5.0 


2.4 


l| . <l 


Separate 


595 




577 


10.0 


18. 0^' 


Separate 



1. Capacity controlled by condition discharge piping and capacity cf force main. 

2. Capacity controlled by force main. 

3. Excluding the 45 mgd capacity pump that has been out of service for many years. 

4. Estimates based on extensive industrial park development in expanded service area, 



U-19 



The older stations, namely Charlestown, East Boston 
Steam, Quincy and Reading, require the most work. These 
stations range from 5^ to 84 years of age. Generally, the 
rehabilitation work consists of providing new heating and 
electrical systems, replacement of drive and pumping units, 
providing adequate ventilation, modifying suction and 
discharge valves and piping, and installing new or addi- 
tional bar screens. 

At most pumping stations, it is anticipated that new 
drive units v/ould consist of electric motors or drives of a 
type that can be controlled to regulate their speed in 
accordance with the level of wastewater in the wet well 
and correspondingly the output of the pumps. It is also 
preferred to locate the casing of the pumps below the 
minimum level of wastewater in the wet well, to avoid the 
installation of priming equipment which can be quite 
troublesome from a maintenance and automatic control 
operation standpoint. 

To properly operate a pumping facility and to 
accurately rronitor the wastewater flows within a waste- 
water collection and treatment system, it is necessary to 
continually measure and record the flows that are discharged 
by pumping stations. In many instances, adequate flow 
measuring devices are not available at the existing 
stations. For this reason, the rehabilitation work includes 
the installation of meters for this purpose. 

It is important in certain instances that some of 
the rehabilitation work be undertaken immediately, because 
the ability of the particular station to meet present needs 
under existing conditions is marginal at best. 

It should also be noted, however, that even with 
completion of the designated rehabilitation work, many of 
the stations, possibly excluding the Alewife Brook, East 
Boston Electric and Hingham pumping stations, will not 
conform to present engineering standards for wastewater 
pumping stations. This is because accepted practice for 
stations requires provision of separate wet and dry well 
sections in both substructure and superstructure, adequate 
access to wet wells, dry wells and equipment, adequate 
working areas around bar screens and equipment, wet wells 
designed to reduce septicity problems by minimizing reten- 
tion times, isolated boiler installations, and adequate 
facilities such as cranes, hoists, etc. for removal of 
equipment. Many of these standards cannot be met unless 
the structural arrangement of the existing stations are 
extensively altered and/or expanded. 



4-20 



A brief description of the operational features of 
each of the 10 existing stations presently used together 
with brief comments on improvements and alternatives, 
where appropriate, is presented in Qhapter 6 of Technical 
Data Vol. 9. 

Costs of Recommended Improvements . Improvement 
needs for each of the pumping stations are listed in Table 
6-2 of Technical Data Vol, 9. 

Estimated costs for the rehabilitation or replace- 
ment of the pumping stations are shown in Table 4-8. 



TABLE 4-8. ESTIMATED COST FOR REHABILITATION 
OP REPLACEMENT OF MDC PUMPING STATIONS 



Pumping station 



Work 



Estimated cost, $ 



Alewife Brook 
Braintree-Weymouth 
Charlestown 
East Boston Steani 
East Boston Electric 
Hingharn 
Houghs Neck 
Quincy 
Reading 
Squantum 
Total 



Rehabilitate 

Replace 

Replace 

Replace 

Rehabilitate 

Rehabilitate 

Replace 

Replace 

Replace 

Replace 



712,000 

2,920,000^ 

6,000, 000 (1) 

1,460,000 (2) 

365,000 

390,000 

203,000 

2,220,000^ 



3,042,000 

1,350,000 
19,162,000 



CD 



1. Includes necessary force mains. 

2. Based on serving East Boston only 



Costs are based on January 1975 costs for the Boston 
area at General Construction Engineering News Record (ENR) 
Cost Index of 2200. 

All costs relating to the repair, rehabilitation or 
reconstruction at pumping facilities include the cost of 



4-21 



materials, labor, installation, testing, engineering and 
an allowance of 50 percent for contingencies. 

Costs associated with the operation and maintenance 
of sewage pumping stations varies widely with the flow, 
type of power used to drive the pumps, the age of the 
facilities, and the degree of automation incorporated into 
the design of the facilities. The estimated operation and 
maintenance costs associated with these pumping facilities 
are based on the manner of operation that would be required 
as a result of any improvements made to the stations as 
described in detail in Technical Data Vol. 9. 

Manpower estimates were based on the sizes of actual 
staffs used at similar existing pumping stations. Although 
all stations were automated to some degree, in no cases 
were manpower requirements totally eliminated. Power costs 
were based on a rate charge of 2.2 cents per kwh (kilowatt- 
hour) while maintenance costs were based on actual exper- 
ience with similar sized facilities. 

The estimated annual and operation and maintenance 
costs for the years 1980, 1990 and 2000 are shown in 
Table 4-9. 



TABLE 4-9. PUMPING STATIONS - ANNUAL 
OPERATION AND MAINTENANCE COSTS 

Estimated annual operation and 

maintenance cost(l), $ 

Pumping station 1980 1990 2000 

Alewife Brook 185,200 187,800 189,400 

Braintree-Weymouth 211,100 221,000 244,400 

Charlestown 251,900 237,600 239,600 

East Boston Steam 210,200 154,400 154,600 

East Boston Electric 13,900 13,900 13,900 

Hingham 80,200 90,900 99,400 

Houghs Neck (2) (2) (2) 

Quincy 201,400 186,100 190,700 

Reading 97,800 103,400 109,700 

Squantum 16,300 16,900 18,300 

Total 1,268,000 1,212,000 1,260,000 

1. All costs are in 1975 dollars. 

2. Included with Nut Island WWTP. 



4-22 



Headworks Analysis and Improvements 

The following existing headworks are discussed in 
detail in Chapter 7 of Technical Data Vol. 9: 

Chelsea Creek Ward Street 

Columbus Park Winthrop Terminal Facility 

All of these facilities are of recent design and construc- 
tion. The Chelsea Creek, Columbus Park, and Ward Street 
headworks were placed in operation in 1968, and the 
Winthrop Terminal facility was placed in operation in 
1970. All of these facilities provide pretreatment - 
coarse and fine screening, and grit removal - for the 
wastewaters discharged to the Deer Island Treatment Plant. 
The .Chelsea Creek Headwork is connected to the Deer Island 
main pumping station by a deep rock tunnel approximately 
4 miles in length. The Columbus Park and Ward Street 
headworks are connected to the same pumping station 
through a separate deep rock tunnel approximately 7 miles 
long. The Winthrop Terminal facility is located on the 
site of the Deer Island Treatment Plant is designed to 
normally discharge wastewaters directly to the primary 
sedimentation tanks of that facility. The location of each 
of these facilities is shown on Figure 4-2 (bound in back). 

Description of Facilities . The Chelsea Creek, 
Columbus Park and Ward Street headworks contain bar racks 
and grit collectors for pretreatment of the wastewater 
before it is discharged to the Deer Island Treatment Plant. 
At each installation, the flow through each grit chamber is 
measured by a Parshall flume which permits velocity control 
in each grit chamber. The Columbus Park and Ward Street 
headworks are equipped with both coarse and fine bar 
screens. However, operating experience has indicated that 
the coarse bar screens are not required, and it is antici- 
pated that they will be removed in the near future. Flew 
through the headworks is by gravity. 

V/astewater entering the Winthrop Terminal facility 
passes through coarse and fine bar racks and is pumped to 
a Parshall flume, then flows by gravity through aerated- 
grit chambers to the Deer Island Treatment Plant. With 
completion of the installation of two 60-mgd pumps that 
have been moved from the old Deer Island Pumping Station, 
this facility has an installed pumping capacity of 180 
mgd. The discharge piping from the two 60-mgd pumping 
units is designed so that these pumps may discharge either 
to the grit chambers or to the treatment plant bypass 
conduit. Flows that are discharged to the treatment plant 
are measured by the Parshall flume. 

4-23 



Rehabilitation Needs . Since the Winthrop Terminal 
facility is of very recent construction, this facility has 
no need for any rehabilitation work. 

All of the headworks are of modern design and are 
in conformance with sound engineering practice. However, 
due to the functions that they perform, the equipment 
within them is subjected to very abrasive action by grit 
and corrosive action by sewage. Accordingly, it can be 
anticipated that the need for equipment repair will occur 
frequently, and correspondingly, the maintenance budget 
for the headworks should be made adequate to provide for 
these needs. 

Inspection of the headworks indicate that the fine 
screen cleaning mechanisms, the inclined and horizontal 
grit collectors and the grit ejectors and valves associated 
with them are in need of repair at all of the facilities. 

At all of the headworks, difficulties have been 
experienced with the pneumatic grit ejection systems 
because of rapid erosion of the discharge piping, parti- 
cularly at bends, line stoppages, and the disposition of 
grit at valve locations. Because of the general opera- 
tional difficulties that have been experienced with these 
systems, it would appear warranted to review the design of 
these facilities, and to determine if the piping is of 
suitable material for this type of service. Based on this 
review, alterations might be suggested which would help in 
minimizing the difficulties now experienced. 

Screenings at the Ward Street Headworks are conveyed 
pneumatically to a hopper from which the screenings are 
trucked to Deer Island for landfill disposal. Since the 
pneumatic system at Columbus Park is not used due to the 
condition of the ejectors and the problems with debris 
bridging in the throat of the hoppers, the screenings are 
bagged before they are trucked to Deer Island. This is 
also true at the Chelsea Headworks, where the screenings 
are manually collected and loaded on a truck for disposal 
at Deer Island. The present operational situation indicates 
that there is some need for repairs, and perhaps a review 
of the operational procedures to determine the most 
feasible method of collecting the screenings at each 
headworks. Present plans call for the grit and screenings 
from the headworks to be incinerated at the sludge disposal 
facility at Deer Island. 

Capacity Requirements . The design capacity of each 
of the headworks indicates that each headworks, with the 
exception of Ward Street, has sufficient design capacity to 

4-24 



handle estimated 2000 peak dry-weather flows. Although the 
design capacity of the Ward Street Headworks is given as 
256 mgd, this facility has been reported to have operated 
satisfactorily at rates of flow up to 285 mgd. Based on 
this operational experience, the Ward Street Headworks 
appears to have sufficient capacity for the projected year 
2000 needs. 

The estimated 2000 peak flow for the Winthrop 
Terminal facility assumes that the service area for that 
facility will be limited to Winthrop, Orient Heights, and 
East Boston. However, at times, in excess of 100 mgd may 
be diverted to this facility from the Chelsea Headworks 
through the East Boston Steam or Electric pumping stations. 
At such times, the Winthrop Terminal facility would be 
required to handle flows up to the reported capacity of 
the North Metropolitan Trunk Sewer or on the order of 100 
to 125 mgd. With the two 60-mgd pumps now being installed, 
there will be sufficient pumping capacity to handle flows 
of this magnitude, with the largest pumping unit out of 
service. The grit chambers, which have a design capacity 
of approximately 60 mgd, are located downstream of the 
pumping station and are not designed to handle the total 
installed capacity of the pumping facility. This is 
because it is planned to divert, after pumping, any excess 
flow beyond 60 mgd to the bypass conduit rather than 
routing any excess flow through the grit chambers and the 
treatment plant. It is doubtful that bypassing of excess 
flow wastewaters will be acceptable to the regulatory 
agencies. For short-range planning, grit removal and 
chlorination treatment facilities should be provided for 
any excess flows. For long-range planning, consideration 
should be given to routing all flows from the Winthrop 
Terminal facility to the Deer Island Treatment Plant when 
the treatment plant is expanded to meet future needs. 
These recommendations are contingent on the fact that 
future studies will indicate that diversion of excess 
flows to the Winthrop Terminal facility from the Chelsea 
Headworks through the East Boston pumping stations and 
the North Metropolitan Trunk Sewer is recommended. 

Although each of the headworks is estimated to have 
sufficient capacity to meet 2000 peak dry-weather flow 
needs, under present conditions, they do not have suffi- 
cient capacity to handle peak inflows. This is because 
they all receive large quantities of storm inflow since 
they serve extensive combined sewered areas. The situa- 
tion at some of the headworks is further aggravated by 
the saltwater inflow that is received due to faulty 
operating tide gates. However, this situation is now 



4-25 



being corrected through a tide gate repair and replacement 
program which is discussed in Technical Data Vol. 2. 

Presently, excess flows tributary to the Ward Street 
and Columbus Park headworks up to the capacity of the 
existing systems back up in the Charles River Valley Sewer 
or in the Columbus Park connection to Boston's Dorchester 
Interceptor. At such times, the excess flow in the 
Charles River Valley Sewer up to the capacity of the 
existing system is diverted to the Cottage Farm storm 
detention and chlorination station temporary storage or 
for treatment before discharge to the Charles River. 
When the depth of flow in the Columbus Park Headworks 
connection reaches an excessive level, Boston 1 s Calf 
Pasture Pumping Station is placed in operation and excess 
flow up to its capacity is diverted to a large sewer and 
thence to Boston's Moon Island tanks for discharge into 
the harbor by the City of Boston. Excess flows at the 
Chelsea Creek Headworks up to the capacity of the North 
Metropolitan Trunk Sewer are diverted to the Winthrop 
Terminal facility. Inflows to the various sewers beyond 
the capacity of the above systems overflow into various 
receiving waters through the numerous combined sewer 
overflows as discussed in Chapter 2. 

It would be very costly to increase the capacity 
of the headworks to provide for peak storm inflows. This 
is because the headworks, tunnels and the Deer Island Treat- 
ment Plant into which they discharge have been designed to 
operate integrally, handling only flows slightly greater 
than peak cry-weather flows. To increase the design 
capacity of the headworks for all inflows would require a 
large increase in capacity of the tunnels which serve 
them. Furthermore, it is not likely that elimination of 
inflows by complete separation of the combined systems 
that are served by the headworks will be economically and 
environmentally justifiable. For these reasons, it would 
seem prudent to continue the present mode of operation of 
these facilities at times of storm inflow until combined 
sewer overflow regulation plans are implemented. However, 
the existing facilities of the Calf Pasture Pumping Station 
should be upgraded to provide modern mechanically cleaned 
racks and grit chambers ahead of the pumping station, and 
the storage tanks at Moon Island should be equipped with 
skimming and chlorination facilities. The Winthrop facil- 
ity should also be upgraded to provide facilities that 
will permit degritting and disinfection of all flows that 
par-s through that facility, if studies indicate that 
excess flov/s should be diverted to that facility. 



4-26 



For long-range planning, excess flows should be 
handled as part of the overall combined sewer overflow 
regulation plan. \ 

Costs of Recommended Improvements . Since all of the 
headworks facilities are new and their recommended improve- 
ments are not large in scope, estimated costs for the 
necessary repairs at the headworks facilities have not been 
determined as it is felt that detailed in-depth engineering 
analyses are required before any specific recommendations 
and estimates can be made. Many of the minor repairs 
required by the existing equipment can, in all probability, 
be rectified by expansion of the maintenance budget. 
Specific work item costs can only be identified by a 
detailed engineering analyses. 



4-27 



CHAPTER 5 
NUT ISLAND TREATMENT PLANT IMPROVEMENTS 



General 

The plant now serves a population of 63^,000 which, 
because of the reduced service area, is not expected to 
increase much beyond 670,000 people by 2000. For this 
reason and because the areas served have essentially reached 
their limit of growth, it is not anticipated that the 
average daily wastewater flow into the plant would appre- 
ciably increase over the design period. Accordingly, it 
can be expected that any major plant expansion requirements 
would arise from the higher treatment requirements. 

Technical Data Vol. 11, Nut Island Wastewater Treat- 
ment Plant Analysis and Improvements covers the study 
performed to analyze the necessary improvements to the 
primary treatment facilities at the treatment plant, 
together with the work necessary to provide secondary 
treatment capabilities at the facility in accordance with 
Environmental Protection Agency (EPA) minimum treatment 
requirements as shown on Figure 5-1. 

Existing Facilities 

The Nut Island Treatment Plant was designed for an 
average daily flow of 112 rogd and a peak flow of 300 mgd. 
A flow diagram for the plant is shown on Figure 5-2. As 
indicated on the diagram, wastewater from the High Level 
Sewer passes through bar screens, grit chambers and commi- 
nutors and is then pumped to the preaeration tanks. 
Wastewater then flows by gravity through the primary tanks 
and out the outfall system. The outfall system discharges 
to Nantasket Roads in the Outer Harbor. The outfall 
system, including an emergency overflow outfall, has been 
designed to have a capacity of 300 mgd at the highest tide 
of record (El 115.7 MDC Datum). 

The Nut Island Treatment Plant consists of two bar 
screens, six grit chambers, nine comminutors, four mixed- 
flow sewage pumps, five preaeration tanks, six primary 
settling tanks, and four digesters. 

Plant Operations . Approximately 76 positions are 
allocated for the personnel to operate the plant. Of 
these, six undertake administrative and general office 



5-1 




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work, 32 are assigned to operations, 33 are employed to 
maintain the plant, and five provide laboratory control. 

Adequacy of Existing Facilities . The Nut Island 
Treatment Plant was placed in operation in 1952 and it can 
be anticipated that much of the original mechanical equip- 
ment, if it has not already been replaced, will require 
rehabilitation or replacement in the near future. 

The condition of the existing equipment as noted in 
Chapter 2 of Technical Data Vol. 11 are based on the inven- 
tory survey, plant inspections, interviews with plant staff, 
and review of previous reports concerned with the condition 
of the existing equipment at the plant. 

Primary Expansion 

This section discusses the need for upgrading the 
existing preliminary and primary treatment facilities and 
providing additional facilities at the Nut Island Treatment 
Plant. Most of the existing, facilities could be used in an 
upgrading situation, but certain components of the existing 
plant, mainly the primary tanks, would require extensive 
work before they could be used to fulfill not only their 
intended function of handling flows approximately equal to 
those received at present, but also meeting higher effluent 
standards . 

Basic Design Criteria . The basic design criteria 
developed for expansion of the existing primary plant are 
presented in Table 5-1. 

The flows have been developed in accordance with 
Technical Data Vol. 2. The flows allow for major and minor 
industrial, commercial and residential wastewater flows and 
include an allowance for infiltration. Major industrial 
flows were determined by survey. Peak-day flows have been 
estimated by applying appropriate factors to dry-weather 
flows. Peak-day flows include an allowance for peak-wet 
weather rates of infiltration. 

A peak flow of 310 mgd used for design represents 
the maximum capacity of the incoming High Level Sewer. 

Present BOD5 and SS loads were determined by computer 
analysis of existing plant data covering the period from 
January 1970 to December 1972, inclusive. This analysis 
established the yearly average and peak one-day loads for 
both BOD5 and SS. 



5-4 



TABLE 5-1. BASIC DESIGN CRITERIA 
NUT ISLAND PRIMARY EXFANSION 



Present 



2000 
design 



2050 



Flow, mgd 

Average day 
Peak day 
Peak 



BOD r , lb/day 

Average 
Peak 



SS, lb/day 

Average 
Peak 

Grit chambers 

Number of units 

Unit length, ft 
Unit width, ft 
Unit depth, ft 

Overflow rate, gpd/sq ft 

Average day 
Peak day 
Peak 

Pumping station 

Flow, mgd 

Average day 
Peak day 
Peak 

New aerated grit chambers 

Number of units 

Unit length, ft 
Unit width, ft 
Unit depth, ft 



127 


130 


150 


211 


224 


251 


310 


310 


310 



149,000 
363,000 



222,000 
439,000 



25,440 
42,268 
62,099 



201,000 
490,000 



281,000 
556,000 



80 


80 


10.4 


10.4 


15 


15 



26,042 
44,872 
62,099 



127 


130 


211 


224 


310 


310 



74 

22 

15 



221., 000 
538^000 



5-5 



TABLE 5-1 (Continued). BASIC DESIGN CRITERIA 
NUT ISLAND PRIMARY EXPANSION 

2000 
Present design 2050 

Overflow rate, gpd/sq ft 

Average day - 20,000 

Peak day - 34,400 

Peak - 47,600 

Detention period, min 

Peak - 3.4 

Preaeration channels 

Number of parallel units 4 4 4 

Unit length, ft 166 166 166 

Unit width, ft 21 21 21 

Number of series units 1 11 

Unit length, ft 85 85 85 

Unit width, ft 12 12 12 

Detention time, min 

Average day 17.8 17.4 15.0 

Peak day 10.7 10.1 9.0 

Primary tanks 

Number of units 6 9 9 

6 @ 185' x 64' 
3 6 215' x 55 T 

Overflow rate, gpd/sq ft 

Average day 
Peak day 
Peak 



1,788 


1,220 


1,410 


2,970 


2,100 


2,350 


4,364 


2,910 


2,910 



5-6 



TABLE 5-1 (Continued). BASIC DESIGN CRITERIA 
NUT ISLAND PRIMARY EXPANSION 

_ __ 

Present design 2050 

Chlorine contact 

Detention period, min 
approximately (1 ) 

Outfall and effluent 
conduit 

Average 37 . 36 

Peak 15 15 

Effluent pumping station 

Flow, rngd 

Average day 127 130 

Peak 310 310 

Outfall 

Diameter, ft - 5 

Length, ft - 5,100 

1. Assumes effluent conduit flows essentially full. 

A present average load of 149,000 pounds of BOD^ per 
day and 222,000 pounds of SS per day are equivalent to a 
daily per capita contribution of 0.24 pounds of BOD5 and 
0.35 pounds of SS. To determine future average BODc and 
SS quantities, the BODq per capita contribution has been 
increased to 0.30 pounds per day and the SS per capita 
contribution to 0.42 pounds per day. 

Analysis further established peak one-day loads and 
the ratio between average and peak loaus was thus deter- 
mined. This ratio was then used to forecast peak one-day 
loads. 

Preliminary Treatment Facilities . There are diffi- 
culties in the operation of the preliminary treatment 
facilities at influent flows in excess of 210 rngd. Since 
these unit processes would continue to experience peak 



5-7 



influent flows in excess of 210 mgd, some modifications or 
expansion of the existing facilities would be required. 
Recognizing the large capital investment that has been made 
in these facilities, various alternatives were studied 
which would permit them to be fully utilized in an upgrading 
situation. 

Preliminary studies indicate that such an arrange- 
ment, as shown diagrammatically on Figure 5-3, could be 
used to successfully incorporate them in an expanded plant 
facility. 

In the recommended plan, the existing bar screens 
would be removed, new bar screens would be placed in the 
inlet section of the existing grit chambers, the comminu- 
tors would be removed, and aerated grit chambers would be 
constructed downstream from the main pumping facility. 

The relocation of the bar screens would subject them 
to acceptable momentum forces since the velocities at their 
new location would be much smaller at peak flows than they 
now experience. 

The removal of the comminutors would eliminate the 
hydraulic head loss though them, and with other channel 
modifications would tend to minimize at peak flows the 
amount of surcharge now being experienced in the system. 

In order to capture any grit that would pass through 
the existing preliminary treatment system, four aerated 
grit chambers would be constructed downstream of the 
existing main pumping station. These grit chambers would 
provide a three-minute detention period at peak flows. 

The existing screening and grit incinerator would 
be retained to serve both the new and existing grit 
facilities . 

r ;i'it Chambers . The six existing grit chambers which 
are of the rectangular type would remain in service. They 
would be reequipped as necessary with new chain flights and 
collectors. The grit would be conveyed pneumatically to 
the grit hopper and incinerator system as it is now. 

The new grit chambers to be added would be of the 
rated type with grit collection achieved by means of an 
overhead clam bucket arrangement. The collected grit 
would be stored in bins from which the grit would be 
conveyed to the existing incineration system. 



5-8 



i 



■MEDIUM BAR SCREEN 
(TO BE REMOVED) 



MEDIUM BAR SCREEN 
(TO BE REMOVED) 



NEW BAR 
SCREENS 





NEW BAR 
SCREENS 




GRIT CHAMBERS 







COMMINUTORS 
(TO BE 
REMOVED) 

3 




NEW BAR 
SCREENS 









PUMP SUCTION WELL 



MIXED FLOW PUMPS 



NEW 
AERATED 

GRIT 
CHAMBERS 



TO PRIMARY TREATMENT 

FIG. 5 3 
DIAGRAMMATIC LAYOUT REVISED PRELIMINARY TREATMENT FACILITIES 
NUT ISLAND WASTEWATER TREATMENT PLANT 



Pumping Station . The existing facility contains 
four pumping units each rated at 83.5 mgd against a dis- 
charge head of 10.3 feet. The combined capacity of these 
units (334 mgd) would be sufficient to meet the projected 
peak flow over the design period. However, head require- 
ments may be increased due to the additional downstream 
hydraulic losses that would be incurred by conveying 
wastewaters to, through, and away from the new aerated grit 
chambers. Modifications that would : increase the available 
discharge head can be achieved either by increasing the 
operating speed of the pumping units or by installing new 
types of impellers. In any event, if required, new pumping 
units may be installed. A detailed analysis to determine 
the most economical selection is beyond the scope of this 
study, but should be undertaken at the time of design. 

Preaeration Tanks . The preaeration tanks consist of 
four units in parallel and one in series, all equipped with 
sparger swing-type diff users. In the upgraded plant, all 
units would be maintained in service. The swing-type 
diffusers need replacement and we would recommend that they 
be replaced where possible with fixed-type diffuser systems 
This is because our experience indicates that fixed-type 
diffuser systems are less costly to maintain. 

Primary Tanks . It is recommended that the existing 
six primary tanks be supplemented by three tanks, all 
equipped with covers. This will permit the primary facili- 
ties to ^operate at overflow rates Cgpd (gallons per day) 
per square foot) of 2,910 under peak flow conditions. We 
have increased the number of primary tanks because without 
doing so, we would anticipate that solids would be washed 
out of the existing primary tanks at peak flows due to the 
excessive overflow rates. 

The three new tanks would have slightly different 
dimensions than the existing tanks to insure that they 
could be located within the limits of the existing site. 
Accordingly, with this modification, additional land would 
not be required. 

Outfall Systems . The existing outfall system, 
as shown on Figure 5-4, consists of two long outfalls 
(5,830 and 5,545 feet), a shorter outfall (1,412 feet), 
and an emergency overflow weir with a shoreline discharge. 
The emergency overflow weir should be abandoned since the 
discharge of primary effluent directly to the shoreline of 
Nut Island under any conditions would not be acceptable. 
In addition, the shorter outfall should be extended by 
approximately 5,000 feet and provided with diffusers at 



5-10 




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which point, approximately 30 feet of submergence would 
be available at mean low water. This extension would 
permit all three outfalls to be used at all times. 

Chlorination Facilities . Pre- and postchlorination 
is practiced at the Nut Island Treatment Plant. For this 
purpose, the plant is equipped with four chlorinators, each 
having a capacity of 8,000 pounds per day. The total 
capacity of the installation is 32,000 pounds per day. 

It is recommended that the existing chlorinators and 
their appurtenant equipment be removed from their present 
location in the Administrative Building to a new building 
constructed for this specific purpose. A new chlorine feed 
system should be provided that would permit receipt of 
chlorine in tank truck lots. 

The capacity of the existing chlorination systems 
should be increased to provide for prechlorination of the 
incoming wastewaters and for standby facilities. 

With three long outfalls in service, the. outfall 
system in conjunction with the existing effluent conduits 
would provide a 15-minute retention period. 

Effluent Pumping Station . Preliminary studies indi- 
cate that an effluent pumping station may be needed. A 
preliminary hydraulic profile for the primary treatment 
plant from the primary effluent weirs to the end of the 
outfalls" (three in service) is shown on Figure 3-2 of 
Technical Data Vol. 11. The profile indicates that at 
maximum tide of record El 115.7 (MDC Datum) and peak flow 
310 mgd, gravity discharge from the primary tanks to the 
sea would not be possible. It is estimated that approxi- 
mately 1 percent of the time it would be necessary to 
operate this pumping facility to discharge treated effluent 

The station would be equipped initially with five 
pumping units, each capable of pumping 78 mgd against a 
head of approximately 22 feet. This would provide an 
available capacity of 310 mgd with the largest pumping 
unit out of service. 



Scum Incinerator Building . Current sludge manage- 
ment planning indicates that sludge removed by the primary 
process would be thickened at the Nut Island site. The 
thickened sludge would then be pumped through dual force 
mains to Deer Island for further processing. To reduce the 
level of maintenance required to keep the transfer force 



5-12 



mains in service, scum would not be included in the transfer 
processes. This is because scum contains a larger percent- 
age of grease which could quickly plug the transfer force 
mains through grease buildup. Therefore, any scum collected 
in the treatment process would be disposed of on the site. 
Such disposal should be by incineration. Scum has been 
successfully incinerated at many installations including 
the Nut Island Treatment Plant. 

Sludge Handling Facilities . For this study, the 
processing and disposal of sludge from the Deer and Nut 
Island treatment plants is as reported in a 1973 report 
by Havens and Emerson, Consulting Engineers, entitled 
A Plan for Sludge Management . * 

Secondary Extension 

Secondary treatment would be required in accordance 
with EPA requirements mentioned earlier. The activated- 
sludge process employing step aeration was selected to 
achieve secondary treatment. During detailed facilities 
planning, other processes including other activated-sludge 
process variations should be investigated. 

The unit processes that constitute an activated- 
sludge process consist of aeration and final tanks. These 
unit processes are discussed in the following paragraphs. 

Basic Design Criteria . The basic design criterial 
relative to the secondary extension of the Nut Island 
Treatment Plant are presented in Table 5-2. 

Aeration Tanks . Twelve aeration tanks, each 80 feet 
wide and 224 feet long and 15 feet deep, would be required 
to handle the projected BODr loads under design conditions. 
Each tank would be so arranged that it would have four 
passes. Proper channeling would be provided so that the 
effluent from the. primary system may be added at the head 
end of each pass. This flexibility in applying wastewater 
to the aeration tanks can be extremely advantageous in 
controlling the operational process. 

Final Tanks . Sixteen circular tanks, each having a 
diameter of 145 feet, would be provided. Each tank would 



*Havens and Emerson Consulting Engineers, Plan for Sludge 
Management , prepared for the Commonwealth of Massachusetts, 
Metropolitan District Commission, August 1973. 



5-13 



TABLE 5-2. BASIC DESIGN CRITERIA SECONDARY 
EXTENSION - NUT ISLAND 



Present 



2000 

design 



050 



Flow, mgd 

Average day 
Peak day 

Peak 

Aeration tanks 

BODr, lb/day ^ x) 

Average day 
Peak day 

Number of units 

Unit length, ft 
Unit width, ft 
Unit depth, ft 

Loading, lb of BOD5/ 
1,000 of 

Average 
Peak 



130 
224 
310 



160,800 
392,000 

12 

224 
80 
15 



50 

121 



150 

251 

310 



176,800 
430,000 

14 

224 
80 
15 



47 
114 



Final tanks 

Number of units 

Type 

Diameter, ft 

Depth, ft 

Overflow rate, gpd/sq ft 

Average day 
Peak 





16 


C: 


Lrcular 




145 




15 




490 




1,170 



16 
Circular 

145 
15 



570 

1,170 



i. Includes recycle load. 



5-14 



be equipped with a sludge and scum removal mechanism. 
According to the present sludge management planning, the 
waste-activated sludge would be thickened through the use 
of flotation thickeners. The thickened sludge would be 
pumped to Deer Island for further processing. Four return 
and waste-activated sludge pumping stations are provided 
since preliminary planning indicates that the sludge piping 
arrangement between final and aeration tanks can be 
minimized. 

While shorter sludge detention times are desirable 
and achievable with circular units, limited space available 
may dictate use of rectangular tanks in final design. 

Chlorination Facilities . Since the peak flow- 
through the plant would not increase with the addition of 
secondary treatment, there will be no need to increase the 
capacity of the chlorination installation. 

Based on preliminary layouts, 15 minutes' retention 
time should be available in the effluent conduit and out- 
fall system. For this reason, chlorine contact basins 
have not been provided. However, in plant layouts, space 
has been provided for them along with a cost allowance in 
the event they are required by the regulatory authorities. 

Effluent Pump Station . With expansion of the plant 
from primary to secondary treatment, the capacity of this 
facility need not be increased since the peak flow would be 
the same as that established for the primary plant. Due to 
the additional hydraulic losses within the secondary 
system, we estimate that the pumps would be required to 
discharge against a maximum head of approximately 29 feet. 
The pumping facility should be required to operate approxi- 
mately 3^ percent of the time, provided that three outfalls 
are available for service. 

Site Requirements 

Nut Island was originally a four-acre island that 
has been filled and connected to the mainland commencing in 
1893 to its present 17-acre size. The Island is totally 
occupied by the primary treatment plant and has no major 
topographic features, is leveled and the shore is surrounded 
by a steep riprap wall. 

Although the Nut Island site is limited in develop- 
able area, the three additional primary tanks that would 
be required in conjunction with secondary treatment can be 
provided without additional filling. However, the filling 



5-15 



of 3.3 acres would be required initially to allow for the 
construction of an operations building, aerated grit 
chambers and a new administration building. 

The major problem in developing the site is provid- 
ing sufficient area for the secondary treatment process. 
To accommodate the aeration tanks, blower building,, final 
tanks, ana a sludge processing building would require some 
additional 2^.8 acres of fill as shown on Figure 5-5. 

Developing Nut Island further for adequate waste- 
water treatment purposes was selected and detailed out for 
purposes of developing construction and operation cost 
budgets . 

The recommended plan would require approximately 
an additional 24.8 acres of fill for secondary treatment. 
The fill area would be limited to the west side of the 
Island in the recommended alternative. 

The site would be developed to an elevation of 126 
feet (MDC Datum) which is the approximate level of the 
existing island. 

It should be noted that it may be possible to 
support the new facilities on a concrete slab which is 
in turn supported on piles. Whether or not this approach 
may be more economical than placing fill should be deter- 
mined at the time of design. 

The site as developed is large enough to accommodate 
the necessary facilities, including a sludge disposal 
building. Under present sludge management planning, it is 
intended to pump thickened sludge from Nut to Deer Island 
for further processing. Except for the site costs, the 
cost of sludge processing is excluded from this report, 
but may be found in another study.* In the event this plan 
is carried through, then there would be no need for a 
sludge disposal building at this site. 

The estimated cost for providing all of the facili- 
ties required for secondary treatment, excluding any sludge 
management facilities, is given in Table 5-3. 



*Havens and Emerson, Consulting Engineers, A Plan for 

3 1 u (J g e Ma n a g e m e n t , prepared for the Commonwealth of 

ssachusetts, Metropolitan District Commission, August 
1973. 



[ j-lG 




LEGEND 
FIRST STAGE-PRIMARY EXPANSION 
SECOND STAGE-SECONDARY EXTENSION 



• 



80 



80 160 



SCALE IN FEET 



LUDGE PUMPING 
BLDG. 



FIG. 5-5 NUT ISLAND WWTP LAYOUT 
RECOMMENDED PLAN 



TABLE 5-3. CONSTRUCTION COST - NUT ISLAND 
• WASTEWATER TREATMENT PLANT U) 

Item Cost, $ 

Site development 23,516,000 

Primary tanks ^ 2 ^ 2,593,000 

Aerated grit chambers 4,683,000 

Aeration tanks 15,080,000 

Final tanks 12,478,000 

Conduits-galleries 9,593,000 

Chlorine contact tanks 2,539,000 

Chlorine equipment and housing 487,000 

Scum incinerator 587,000 

Effluent pump station 4,196,000 

R.S. and W.A.S. pump station 3,907,000 

Revamp existing primary and influent 

pump station 13,485,000 

Operations building 3,686,000 

Administration building 1,431,000 

Blower building 10,017,000 

Outside piping and landscaping 10,821,000 

Electrical and instrumentation 13,101, 000 

Plant Cost 132,200,000 

Outfall Cost 5,036,000 

Total 137,236,000 

1. Additional costs for sludge management are presented in 
A Plan for Sludge Management for the Metropolitan Dis- 
trict Commission , Havens and Emerson Limited, August 
1973, available at the Metropolitan District Commission. 

2. Additional cost for covers $4,132,000. 

5-18 



The estimated cost Is based on an ENR (Engineering 
News-Record) Index of 2200 and includes a 35 percent allow- 
ance for engineering and contingencies. The cost does not 
provide for flotation thickeners, sludge disposal facili- 
ties or other appurtenant sludge management equipment. 
The estimated cost does not include legal fees or interest 
during construction. 

Phased Development and Costs 

The existing Nut Island Treatment Plant provides 
primary treatment and was designed for an average daily 
and peak flow of 112 and 300 mgd, respectively. These 
flows are slighly smaller than the corresponding design 
projected flows of 130 and 310 mgd. It would appear then 
that, with minor modifications, the plant could be revamped 
to meet primary design requirements. For several reasons, 
however, this is not the case. The existing primary tanks 
have settled, rendering them ineffective with relationship 
to scum removal and inefficient with regard to solids 
removal. Since the time these primary tanks were designed, 
design parameters have been upgraded to meet higher 
effluent standards. These upgraded design parameters, as 
indicated in Chapter 2 of Technical Data Vol. 11, would 
require the construction of three additional primary tanks. 
Furthermore, there are some operational difficulties 
within the preliminary treatment system. 

The first priority should be to revamp and provide 
such new facilities that would permit the existing primary 
treatment plant to operate efficiently and effectively 
when handling the design flows. 

The second-phase development would consist of pro- 
viding those facilities that would permit secondary 
treatment . 

First-Phase Construction Costs . Under the first- 
phase development, the work would consist essentially of 
revamping the existing primary tanks and the influent 
pumping station, providing aerated grit chambers, an 
effluent pumping station, an operations building, upgrading 
the existing chlorination facility, and extending the short 
outfall conduit. The cost of doing this work is presented 
in Table 5-4. 

Second-Phase Construction Costs . This work consists 
mainly of the construction of those facilities that would 
be required to provide secondary treatment. In addition 



5-19 



to the facilities previously described, a new administra- 
tive building would be provided and the operation building 
extended to meet the requirements of a secondary plant. 
The estimated cost of providing all these facilities is 
set forth in Table 5-5. 

TABLE 5-4. FIRST-PHASE CONSTRUCTION COSTS (1) 

Item Cost , $ 

Site development 3,559,000 

Primary tanks 2 , 593, 00(r 2 ^ 

Aerated grit chambers 4,683,000 

Operations building 2,304,000 

Effluent pump station 4,196,000 

Chlorine contact tanks 2,539,000 

Conduits-galleries 2,859,000 

Chlorination equipment and housing 487,000 

Scum incinerator 587,000 

Revamp existing primaries and influent 
pump station 13,485,000 

Outside piping and landscaping 3,696,000 

Electrical and instrumentation 4 ,512 , 000 

Plant Cost 45,500,000 

Outfall Cost 5,036,000 

Total 50,536,000 

T~. Sludge management costs are in addition to these. 
2. Additional cost for covers - $4,132,000. 



Operation and Maintenance Cost . The annual operat- 
ing and maintenance costs that would be incurred during 
the first-phase and second-phase operational period are 



5-20 



presented in Table 5-6. During the first phase of opera- 
tion, it is assumed that all power requirements would be 
supplied from the plant's internal electrical generation 
system. 

TABLE 5-5. SECOND-PHASE CONSTRUCTION COSTS ^ 

Item Cost, $ 

Site preparation 19,957,000 

Aeration tanks 15,080,000 

Final tanks 12,478,000 

Conduits-galleries 6,734,000 

Administration building 1,431,000 

Blower building 10,017,000 

( ?) 

Sludge pump stations 3,907, 000 v; 

Operations building 1,382,000 

Outside piping and landscaping 7,125,000 

Electrical and instrumentation 8,589,000 

Total 86,700,000 

1. Sludge management costs are in addition to these. 

2. Return sludge and waste-activated sludge. 



The total annual operating and maintenance costs do 
not provide for sludge management. Manpower costs are 
based on today's labor rates and include fringe benefits. 
Fuel costs are computed at a unit price of 35.6 cents a 
gallon and power costs at a unit price of 3 cents per kwh. 
Chemical (chlorine) costs are computed at a purchase price 
of $205 per ton. 



5-21 



TABLE 5-6. ANNUAL OPERATION AND MAINTENANCE COSTS ^^ 

Item Cost, $ 

First Phase 

Manpower (93) 

Operation and maintenance 1,204,000 

Chemical 

Chlorine 486,000 

Maintenance 

Plant 337,000 

Total 2,027,000 

Second Phase 

Manpower (112) 

Operation and maintenance 1,451., 000 

Fuel and electrical power 

Fuel 100,000 

Electrical power 1,050,000 

Chemical 

Chlorine 324,000 

Maintenance 

Plant 664,000 

Total 3,589,000 

1. Sludge management costs are in addition to these. 



CHAPTER 6 
DEER ISLAND TREATMENT PLANT IMPROVEMENTS 



General 

The Deer Island Treatment Plant is designed to pro- 
vide primary treatment for an average daily flow of 343 mgd 
and a peak flow of 848 mgd. A breakdown of the sources of 
these flows is presented in Table 2-1 of Vol. 10. Preliminary 
treatment is provided at four headworks . The headworks 
are discussed in Chapter 4. 

Technical Data Vol. 10, Deer Island Wastewater 
Treatment Plant Analysis and Improvements covers the study 
performed to analyze the necessary improvements to the 
primary treatment facilities at the Deer Island Treatment 
Plant, together with the work necessary to provide secon- 
dary treatment capabilities at the facility. 

Existing Facilities 

A flow diagram for the plant is shown on Figure 6-1. 
As indicated on the diagram, wastewaters from the Main 
Pumping Station and the Winthrop Terminal facility are 
discharged to the treatment plant. 

Wastewater Is conveyed to the Main Pumping Station 
by gravity through two independent tunnel systems. The 
Main Pumping Station is designed to handle an average flow 
of 319 mgd and a peak flow of 788 mgd. The flow from the 
Winthrop Terminal facility which has a capacity to pretreat 
an average flow of 24 mgd and a peak flow of 60 mgd is 
mixed with the effluent from the Main Pumping Station. The 
combined flow (343 mgd average - 848 mgd peak) is then 
discharged to the primary treatment plant. 

The Winthrop Terminal facility has the capability of 
diverting an additional flow of 75 mgd from that facility 
directly to the plant outfall system. This capability will 
be used when excessive storm runoff occurs in the combined 
system which is tributary to that facility. To handle this 
quantity of flow as well as the peak flow through the 
plant, the outfall system has been designed to have a 
capacity of 923 mgd at the highest tide of record (El 115.7 
MDC Datum). 

The Deer Island Treatment Plant consists of two 
preaeration channels, eight primary sedimentation tanks, 
four thickening tanks and four digesters. 

6-1 



• 



note: 



PATH OF FLOW THROUGH WWTP 



COURTESY OF THE METROPOLITAN DISTRICT COMMISSION 



RAW 



SEWAGE 



HEADWORKS 



CHELSEA 




PRETREATED 



£ 

r 



RAW 



SEWAGE 



- ^ r- i / 

COLUMBUS ^ 



WARD 




SEWAGE -V^j /VHEADWOR 



FIG. 6-1 FLOW DIAGRAM - DEER ISLAND 
WASTEWATER TREATMENT PLANT 



Plant Operations . The plant and headworks are 
maintained and operated by a staff of 239 people. Of 
these, approximately 60 are employed at the headworks. Of 
the remaining 179 who are assigned to the plant, 10 under- 
take administrative and general office work, 69 are assigned 
to operations, 91 are employed to maintain the plant, and 
nine are used for laboratory and engineering control 
purposes. 

Adequacy of Existing Facilities 

The Deer Island Treatment Plant was placed in 
service in June of 1968 and has, therefore, been in 
operation for approximately seven years. This operational 
period represents only a short period of the normal operat- 
ing life of most of the equipment at this installation. 
Since this is so and since the equipment has received good 
day-to-day maintenance, it can be anticipated that the 
condition of most of the major equipment is such that it 
can be used in an expanded facility. 

Comments relative to the condition of the major 
elements of the existing facilities, as noted in Chapter 2 
of Technical Data Vol. 10, are based on the inventory 
survey, plant inspections, interviews with plant operating 
staff, and review of previous reports, where such were 
concerned with the condition of the existing facilities 
at the plant. 

Primary Expansion 

The purpose of this section is to discuss the need 
for providing additional primary treatment facilities to 
meet year 2000 needs at the Deer Island Treatment Plant. 
Primary treatment facilities at the present site consist 
of preaeration channels, primary tanks, chlorination 
facilities and an outfall system. As previously noted, 
all of these facilities, some with modification, can be 
used in an upgrading situation. 

Basic Design Criteria . The basic design criteria 
developed for expansion of the existing primary plant are 
presented in Table 6-1. 

The flows have been developed in accordance with 
the techniques and parameters set forth in Technical Data 
Vol. 2. The flows allow for major and minor industrial, 
commercial and residential wastewater flows and include 
an allowance for infiltration. Major industrial flows were 
determined by survey. Peak-day flows have been arrived at 



TABLE 6-1. BASIC DESIGN CRITERIA DEER ISLAND 
TREATMENT PLANT PRIMARY EXPANSION 



Present 



2000 

design 



2050 



Flow, mgd 

Average day 
Peak day 
Peak 



BOD 



5 , lb/day 



Average 
Peak 

SS, lb/day 

Average 
Peak 

Preaeration channels 

Number of units 
Unit length, ft 

Unit width, ft 

Detention time, min 
At average day 
At peak day 

Primary tanks 



336 
8115(1) 



439,000 
930,000 



374,000 

1,128,000 



2 
400 

20 



7.9 

4.8 



400 


430 


731 


782 


930 


930 



555,000 571,000 
1,176,000 1,210,000 



511,000 
1,678,000 



4 4 

2 at 400 2 at 400 

2 at 300 2 at 300 

20 20 



11.6 
6.5 



10.8 
6.1 



■jumber of units 
Unit length, ft 
Unit width, ft 


8 

245 

98 


14 

245 

98 


14 

245 

98 


jverflow rate, gpd/sq ft 
Average day 
Peak day 
Peak 


1,749 
2,983 
4,399 


1,190 
2,174 
2,767 


1,279 
2,326 

2,767 



Chlorine contact chamber 



Number of units 
Unit length, ft 
Unit width, ft 
Unit depth, ft 



2 

320 

72 

15 



6-4 



TABLE 6-1 (Continued). BASIC DESIGN CRITERIA DEER ISLAND 
TREATMENT PLANT PRIMARY EXPANSION 



Present 



2000 
design 



2050 



16 
19 

35 



15 



Detention time, min 
At average flow 
OutfallC 2 ) 

Chamber 

Total 

At peak flow 
Outfall 
Chamber 

Total 

Effluent pumping station 

(Operational frequency 
keyed to hydraulic 
capacity of gravity 
discharge through 
outfall) 

Plow, mgd 
Average day 
Peak day 
Peak 



1. Occurred between 7-1-72 to 6-30-73. 

2. Assumes outfall conduit flows full. 



by applying, according to source, appropriate factors to 
dry-weather flows and include an allowance for peak-wet 
weather rates of infiltration. 

A peak flow of 930 rngc which represents the capacity 
of the incoming pumping facilities has been used for both 

2000 and 2050. 

Present BOD (biochemical oxygen demand) and SS loads 
were determined by computer analysis of existing plant data 
covering the period from Jam ary 1971 to March 1973. The 
analysis established the yearly average and peak one-day 
loads for both BODc and SS. 



336 


440 


573 


731 


845 


930 



- 



A present average load of 439,000 pounds per day 
of BOD5, and 37^,000 pounds per day of SS are equivalent 
to an overall daily per capita contribution of 0.33 pounds 
of BOD5 and 0.28 pounds of SS. To determine future average 
BOD5 and SS quantities, the BOD5 per capita contribution has 
been increased to O.38 pounds per day and the SS per capita 
contribution to 0.35 pounds per day. This increase can be 
expected due to improvement in the standard of living of 
the serviced population with an accompanying increase in 
the use of garbage grinders and in wastage. 

Analysis of present plant operating data established 
peak one-day loads. The ratio between peak one-day loads 
and average loads was then determined, and the ratio so 
determined was used to forecast future peak one-day loads. 

Main Pumping Station - Winthrop Terminal Facility . 
The primary treatment plant receives flow from two sources: 
the Main Pumping Station and the Winthrop Terminal facility. 
It is estimated that under peak flow conditions (923 mgd), 
788 mgd will be contributed by the Main Pumping Station and 
approximately 135 mgd by the Winthrop Terminal facility. 

The main pumping station has a peak capacity of 
810 mgd which is provided by nine pumping units, each of 
which has a Capacity of 90 mgd. Accordingly, the facility 
has sufficient capacity to meet projected peak demands of 
788 mgd. It is recommended, however, that the radial dual 
fuel engines that drive the pumping units be replaced with 
electric motors. 

The Winthrop Terminal facility has been designed to 
screen and pump a peak flow of 135 mgd, 60 mgd of which 
passes through aerated grit chambers before discharge to 
the primary treatment system. The facility is so arranged 
that the remaining 75 mgd can be bypassed around the grit 
removal and the existing primary treatment facilities and 
discharged directly to the outfall system. Since all 
wastewaters will require treatment, this arrangement must 
be modified. This can be done by providing additional grit 
removal facilities and routing the effluent from these new 
facilities as well as from the existing grit . chambers to 
the primary treatment system. 

Preaeration Channels . The existing preaeration 
channels provide retention time of approximately 4.8 and 
7.9 minutes at present peak and average daily flow rates. 
Based on experience elsewhere, these retention times are 
not long enough to permit sufficient pref locculation of the 
wastewater to materially aid the following settling process. 



6-6 



Preaeration does, however, aid in keeping the solids in 
suspension and in improved scum removal. For these 
reasons, the preaeration features of the existing facility 
are retained and expanded. Two additional preaeration 
tanks, each 20 feet wide by 300 feet long, would be 
provided in the expanded facility. The number and the 
size of the additional units has been selected on the 
basis that six additional, primary tanks would be provided. 
With the new units, the retention times at design average 
and peak flows will be increased to approximately 11.6 and 
6.5 minutes, respectively. 

Primary Sedimentation Tanks . The settling perfor- 
mance of primary tanks is related to the surface hydraulic 
loading (overflow rate) which is expressed in units of gpd 
per square foot of surface area. Under present conditions, 
the overflow rates on the average day, peak day and under 
peak conditions are 1,7^9, 2,983 and 4,3^9, respectively 
which were common design parameters. These overflow rates 
when compared to present design standards are considered 
to be excessive. This is particularly true at peak flow 
since we would anticipate that there would be a tendency 
to wash solids out of the tanks at an overflow rate of 
^,3^9 gpd per square foot. For this reason, it is recom- 
mended that the number of primary tanks be increased from 
8 to 14. The resulting overflow rates under design condi- 
tions are satisfactory provided that secondary treatment 
follows the primary treatment process. 

Outfall System . The existing outfall system, as 
shown on Figure 6-2, consists of a single conduit that 
contains three gate chambers A, B and C. At Gate Chamber 
C, the conduit discharges into two submerged outfalls, the 
"Old Outfall" that served the old Deer Island Pumping 
Station and a "New Outfall" that was constructed at the 
same time as the treatment plant. Two bypasses were 
provided in the outfall system, one at Gate Chamber A and 
the other at Gate Chamber C. Both bypasses were designed 
to discharge either directly to or just beyond the Deer 
Island shoreline. Provision was also made at Gate Chamber 
B to interconnect the new outfall conduit to the land 
portion of the outfall system that served the Old Deer 
Island Pumping Station. However, this connection was 
never completed. 

It is recommended that the interconnection at Gate 
Chamber B to the Old Peer Island outfall system be completed 

Chlorination Facilities . Pre- and postchloriation 
is practiced at the Deer Island Treatment Plant. Prechlo- 
rination is not used routinely and is applied only when 

6-7 



# 



deer island 

wastewater 

treatment' 

PLANT 



NORTH 
METRO 
SEWER 




•fr 



WINTHROP 
TERMINAL 
FACILITY 



NORTH METRO 
RELIEF TUNNEL 



BOSTON MAIN 
DRAINAGE TUNNEL 



^t 



&&&> 



-EXISTING 
BULKHEAD 



m 



© 



(ABANDONED) 



OLD D.I. 

PUMP 
STATION 



f 



GATE CHAMBER "B" 
(CONNECTION NOT MADE) 



GATE CHAMBER "C 




LEGEND 

(?) RELIEF OUTFALL A 
Q RELIEF OUTFALL C 

(3) EXISTING OUTFALL (NEW OUTFALL) 
(J) DEER ISLAND OUTFALL (OLD OUTFALL) 
(5) EXISTING TEMPORARY OUTFALL 
mm NORMAL FLOW PATH 

EMERGENCY FLOW PATH 



FIG. 6-2 DEER ISLAND 
WASTEWATER TREATMENT PLANT- 
OUTFALL SYSTEM 



odor control is required or in the event there is a break- 
down in the postchlorination system. 

Present effluent standards require that the effluent 
be disinfected to reduce total coliform levels in accor- 
dance with the criteria established by regulatory agencies. 
In the case cf the use of chlorine for disinfection' this 
would normally require a residual concentration of 1.0 mg/L 
after a 15 minute retention period. Although the actual 
application rate must be determined by test, primary 
effluents usually require a dosage of approximately 12 
mg/L to meet this criteria. At the design period, a 
dosage of 12 mg/L will require chlorine application at 
the rate of 19 9 36 and 46 tons per day under average day, 
peak day and peak conditions, respectively. Since these 
application rates exceed the 29-ton capacity of the 
existing chlorinators (seven at 8,000 lb/day and one at 
2,000 lb/day), additional chlorination facilities may be 
required. These facilities should be sized to provide 
standby equipment. 

Under existing operating conditions, the retention 
time for the chlorination system is provided by the outfall 
system. Calculations indicate that, if the interconnection 
at Gate Chamber B is provided, then the retention time 
within this system will be seven minutes at the design peak 
flow. To increase the retention period to 15 minutes, 
construction of two chlorine retention tanks, each 72 feet 
in width and 320 feet in length, is recommended. 

With secondary treatment required, the elevation of 
the water surface in the chlorine contact tanks will be 
substantially lower than that level which will exist under 
primary treatment conditions. For this reason, the tanks 
should be initially constructed deep enough so that an 
adequate retention period will be obtainable when secondary 
treatment is provided. 

Effluent Pumping Station . A preliminary hydraulic 
profile for the primary treatment plant is shown on Figure 
3-1 of Technical Data Vol. 10. The profile indicates that 
at maximum tide of record El 115.7 feet (MDC Datum) and 
peak flow (930 mgd), gravity discharge from the primary 
tanks to the sea would not be possible. It is estimated 
that approximately 2.5 percent of the time, it would be 
necessary to pump in order to discharge the treated effluent 
The station would be equipped with 10 pumping units each 
capable of pumping approximately 103 mgd against 30 feet 
of head. The need for this pumping station should be con- 
sidered further during detailed facilities planning and 
discussed with officials from the EPA and other regulatory 
agencies. 

6-9 



Sludge Handling Facilities . For this study, the 
processing and disposal of sludge from the Deer and Nut 
Island treatment plants is as reported in a 1973 report 
by Havens and Emerson, Consulting Engineers, entitled A 
Plan for Sludge Management . * 

Secondary Extension 

Extension to secondary treatment is provided to meet 
the minimum treatment established for the Deer Island Treat- 
ment Plant as defined by EPA requirements discussed earlier 
in this report. In this particular situation, the acti- 
vated-sludge process has been selected to achieve this 
treatment. 

The activated-sludge process can be designed using 
various concentrations of biological mass, organic loading 
rates, aeration detention times, sources of oxygen supply, 
and rates of returned sludge. For this reason, many 
process modifications can be developed that will produce 
effluents of similar quality. For purposes of this study, 
the step-aeration modification of the activated-sludge 
process has been selected. During detailed facilities 
planning, other processes, including other activated-sludge 
process variations, should be investigated. 

Basic Design Criteria . The basic design criteria 
relative to the secondary extension of the Deer Island 
Treatment^ Plant are presented in Table .6-2. 

Aeration Tanks . Under design conditions, 20 aera- 
tion tanks, each 370 feet long, 80 feet wide and 15 feet in 
depth, would be required. Each tank would be so arranged 
that four passes, each 20 feet wide, would be available. 
Returned sludge from the final settling tanks would be so 
channeled that the incoming primary effluent may be intro- 
duced at the head end of each pass. 

Studies undertaken for similar sized plants have 
indicated that a diffused air system is more economical 
than a mechanical aeration system to supply the necessary 
oxygen. Accordingly, for costing purposes, a fixed diffused 
air system has been selected. Such a system would require 
the construction of a blower building to house the blowers 
that would supply the diffused air system. 



*Havens and Emerson, Consulting Engineers, A Plan for Sludge 
[ior,age r rient , prepared for the Commonwealth of Massachusetts, 
Metropolitan District Commission. August 1973. 



(-10 



400 


430 


731 


782 


930 


930 



TABLE 6-2. BASIC DESIGN CRITERIA DEER ISLAND 
TREATMENT PLANT SECONDARY EXTENSION 

2000 
^ Present design 2050 

Flow, mgd 

Average day 336 

Peak day 573 

Peak 845 C1) 

Aeration tanks 

BOD r , lb/day (2) 

Average day 444,000 457,000 

Peak 941,000 968,000 

Number of units 20 20 

Unit length, ft 
Unit width, ft 
Unit depth, ft 

Loading, lb of BODc/1,000 
cf) 5 

Average day 50 51.5 

Peak day 106 109 

Final tanks 

Number of units 48 48 

Type Circular Circular 

Diameter, ft 145 145 

Depth, ft 14 14 

Overflow rate, gpd/sq ft 

Average day 505 542 

Peak 1,174 1,174 

T~. Occurred between 7-1-72 and 6-30-73. 
2. Includes 10 percent recycle load. 



370 


370 


80 


80 


15 


15 



6-11 



Each aeration tank would be equipped with a foam 
control system which would consist of a series of jet 
nozzles placed around the periphery of the tank. Screened 
final effluent would be used as a source of water for the 
foam control system. 

Final Tanks . Forty-eight circular tanks would be 
provided, each 145 feet in diameter and 14 feet in depth. 
At a peak flow of 930 mgd, the overflow rate would be 1,174 
gpd per square foot. This rate is low enough to insure 
that the solids within the tank would not be washed out 
with the effluent at times of peak flow. 

Each tank would be equipped with a sludge collection 
system of the suction type to insure timely and complete 
removal of the settled solids. Each tank would also be 
equipped with a scum collection system. 

The sludge taken from the final tanks would be 
conveyed by gravity to return and waste activated-sludge 
pumping stations. One return and waste sludge pumping 
station would be provided to serve 2 4 final tanks. The 
return sludge pumping station would be equipped with 
variable-speed pumps so that the rate of return sludge may 
be modified t'o meet different operational requirements. 
While shorter sludge detention times are desirable and 
achievable with circular units, limited space availability 
may dictate use of rectangular tanks in final design. 

Effluent Pumping Station . Since the peak flow 

through the secondary plant is the same as that established 

for the primary plant, there will be no need to increase 
the capacity of this facility. 

A preliminary hydraulic profile for the secondary 
treatment plant is shown on Figure 4-1 of Technical Data 
Vol. 10. As indicated in that profile, at times of peak 
flow (930 mgd) and maximum tide of record El 115.7 (MDC 
Datum), gravity discharge would not be possible. Due to 
the additional hydraulic loss within the secondary system, 
the pumps will be required to discharge against a maximum 
head of approximately 37 feet. When the primary effluent 
pumping station is constructed, this condition should be 
recognized so that the pumps may be readily modified at a 
later date to meet the new head-discharge conditions. 

The pumping facility would be required to operate 
approximately 25 percent of the time. 



6-12 



Primary Tanks and Chlorinatlon Facilities . Since 
the design of both of these facilities is on the basis of 
peak flows and since the estimated peak flow is not changed 
with the secondary expansion, these facilities would not 
require modification. 

Site Requirements 

Deer Island is presently occupied by a County House 
of Correction, the Deer Island Treatment Plant and an 
inactive military installation. The Boston Harbor Islands 
Comprehensive Plan* recommends that the southern portion of 
the island that is occupied by the inactive military 
installation be developed for recreational purposes. The 
plan also recognizes that land will be required for expan- 
sion of the Deer Island Treatment Plant. For this purpose, 
it recommends the use of the site of the correctional 
institution and some 10 acres of fill on the north side of 
the Island. 

The major topographic feature on the island is a 
drumlin that rises some 100 feet above sea level, and 
which is located just south of the existing Deer Island 
Treatment Plant. This natural geological feature has a 
high potential for development for recreational use as 
well as enhancing the natural appearance of the Harbor. 

Expansion of the existing primary treatment facili- 
ties presents no particular difficulties. From an engineer- 
ing standpoint, expansion of the primary tanks is best 
accomplished through construction of similar units adjacent 
and to the east of the existing facilities. Since six more 
primary tanks can be so arranged all within the existing 
MDC property, this expansion is not in conflict with the 
other proposed uses of Deer Island. 

The major difficulty in site development is finding 
sufficient area to accommodate the aeration and final tanks 
that are required to provide secondary treatment. This is 
evident when it is recognized that these facilities will 
occupy approximately 75 acres, an appreciable portion of 
the total 210 acres of land on Deer Island. 



* Boston Harbor Islands Comprt hensive Plan for Massachusetts 
Department of Natural Resources, by Metropolitan Area 
Planning Council, October 1972. 



6-13 



Because it is the intent to develop the Island for 
multi-purpose use with a minimum amount of fill, five site 
options were considered. These options are described in 
Technical Data Vol. 10 together with the noted advantages 
and disadvantages of each. 

The recommended plan is shown on Figure 6-3 and the 
advantages and disadvantages of such a layout are presented 
in Table 6-3. This layout would require fill (some 14 
acres), at some loss in the most appropriate engineering 
arrangement of aeration and final tanks. The arrangement 
of aeration and final tanks as indicated has been investi- 
gated as to layout of influent and effluent piping, returned 
sludge piping, etc. This investigation indicates that the 
proposed layout is workable, without utilizing any unusual 
internal pumping facilities. Under this plan, the main 
entrance road to the recreational area at the southern tip 
of the island would pass through the treatment plant. 
However, this arrangement should impose no difficulty in 
either access to the recreational area or in the day-to-day 
operation of the plant. 

Phased Development and Costs 

The estimated construction cost for the Recommended 
Plan is based on an ENR Index of 2200 and includes a 35 
percent allowance for engineering and contingencies. The 
costs do not provide for electrification of the main pump- 
ing station, for securing outside sources of power, land, 
legal fees or interest during construction. 

The existing Deer Island Treatment Plant was designed 
for an average daily and peak flow of 34 3 and 848 rngd, 
respectively. Since the estimated design flow rates exceed 
these values, the first priority is to upgrade the existing 
facilities to meet these new flow requirements. As part of 
this upgrading procedure, the existing facilities should be 
expanded or revamped to meet the latest acceptable water 
quality effluent standards. Such a program is discussed 
and outlined in Chapters 2 and 3 of Technical Data Vol. 10. 

The second-phase development of the Deer Island 
Treatment Plant would be to provide secondary treatment. 
This level of treatment would permit discharge of the 
effluent to the outer harbor through the existing outfall 
system in conformance with agreements with the regulatory 
agencies. 



6-14 



LIMITOF FILL 



BLOWER BUILDING 

LIMITOF FILL 




EFFLUENT 

PUMPING 

STATION 



PRIMARY 

EFFLUENT 

OUTFALL 



LEGEND 

EXISTING FACILITIES 

FIRST STAGE-PRIMARY EXPANSION 

SECOND STAGE-SECONDARY EXTENSION 

PRIMARY EXPANSION FOR OCEAN DISCHARGE 
OR CHEMICAL COAGULATION 



LOCATION FOR PROPOSED 
SLUDGE MANAGEMENT 
FACILITY"(BY OTHERS). 



• 



300 o 300 600 

SCALE IN FEET 



FIG. 6 3 DEER ISLAND WWTP - 
SITE OPTION 5 - RECOMMENDED PLAN 



TABLE 6-3. 



ADVANTAGES AND DISADVANTAGES OF THE 
RECOMMENDED PLAN 



Advantages 



Disadvantages 



1. Drumlin is not disturbed. 1. 



2. Prison facilities can be 2. 
located on drumlin with- 
out filling at some loss 

in recreational land. 

3. Southern tip of Deer 3. 
Island preserved for 
recreation and continued 

use of existing facilities. 



4. Minimizes fill require- 4. 
ments. 



5. Primary and secondary 

treatment facilities, as 
well as sludge process- 
ing facilities, are self- 
contained in one area 
for ease of operation and 
maintenance of plant. 



It will be necessary to 
construct some secondary 
facilities in fill which 
will require pile foun- 
dations. 

No excess fill generated 
for use at Nut Island. 



Increases length of 
piping galleries and 
pumping requirements for 
transport of waste acti- 
vated sludge to sludge 
processing facilities. 

Notable impact on recrea- 
tion aspects of Eastern 
Shoreline of Deer Island 



This discussion is limited to the wastewater treat- 
ment and does not include the development of those facili- 
ties required for sludge management. The development of 
such facilities would be required concurrently, added to 
the phased program outlined here. 

First-Phase Construction Cost . The first-phase 
development would consist of constructing additional 
primary tanks, chlorination facilities and a new effluent 
pumping station. The cost of providing these facilities is 
presented in Table 6-4. 



6-16 



TABLE 6-4. CONSTRUCTION COST - FIRST PHASE (1) 

Item Cost, $ 

Primary tanks 10,431,000 

Chlorine contact tanks 6,614,000 

Effluent pumping station 11,711,000 

Channels- conduits-galleries 5,-588,000 

Outside piping, roads and grading 3,400,000 

Electrical and instrumentation 4,156,000 

Total 41,900,000 

T~, Costs for sludge management first-phase program for 
combined Deer and Nut Island plants must be added. 



Second-Phase Construction Cost . The construction of 
aeration tanks, final settling tanks, return sludge pumping 
stations, and other appurtenant work would be undertaken 
under the second phase of the program. The cost of these 
facilities is set forth in Table 6-5. 

TABLE 6-5. CONSTRUCTION COST - SECOND PHASE ^ 

Item Cost, $ 

Aeration tanks 33,578,000 

Final tanks 37,778,000 

Return sludge pumping station 6,138,000 

Blower building 23,840,000 

Channels-conduits-galleries 8, 038, 000 

Operations building 2,534,000 

Storage building 520,000 

Outside piping, roads and grading 11,267,000 

Electrical and instrumentation 12,394,000 

Extraordinary site development 13, 913, 000 

Total 150,000,000 

1. Costs for sludge management second-phase program for 
combined Deer and Nut Island plants must be added. 



Operation and Maintenance Costs 

The annual operating and maintenance costs for first- 
phase and second-phase development at Deer Island are set 
forth in Table 6-6. 



6-17 



TABLE 6-6. ANNUAL OPERATING AND MAINTENANCE COST 



(1) 



Item . Cost, $ 

First Phase 

( ?) 
Manpower (169) 

Operation and maintenance 2,189,000 

Fuel and electric power 

Fuel 146,000 

Electric power 1,809,000 

Chemical 

Chlorine 1,496,000 

Maintenance 453,000 

Total 6,093,000 

Second Phase 

Manpower (221) ^ 

Operations and maintenance 2,862,000 

Fuel ~and electric power 

Fuel 190,000 

Electric power 4,041,000 

Chemical 

Chlorine 998,000 

Maintenance 1,175,000 

Total 9,266,000 

1. Operation and maintenance costs for sludge management 
facilities serving both Deer and Nut Island plants are 
reported In Havens and Emerson Consulting Engineers, 

A Plan for Sludge Management , prepared for the Common- 
wealth of Massachusetts Metropolitan District Commis- 
sion, August 1973. 

2. Manpower requirements to operate and maintain the treat- 
ment plant, headworks and. the Deer Island Pumping 
Station, but does not include the manpower related 

to the sludge management facilities. 

6-18 



CHAPTER 7 
CONSTRUCTION STAGING AND COST DISTRIBUTION 



General 

The Construction Staging Program reflecting the 
various projects (improvements and/or additions) to be 
undertaken in accordance with the recommended plan is 
presented on Figure 7-1. This schedule represents the final 
sequence of projects, that was adopted to meet regulatory 
agency requirements following an earlier construction 
schedule selected by the technical subcommittee and pre- 
sented in Chapter 7 of Vol. 6 as a construction staging 
alternative entitled Postponement of Secondary Treatment. 

As shown on Figure 7-1* the total estimated construc- 
tion cost for all of the related work is in excess of $855 
million. Present legislation authorizes the U. S. EPA to 
pay 75 percent of this cost and the Massachusetts Division 
of Water Pollution Control to pay another 15 percent, with 
the remaining 10 percent expected to be paid for by the MDC 
member communities. However, because appropriations are 
expected to be limited for any given year during the time- 
table of the proposed construction program (present through 
the year 2000), sequence numbers have been assigned to 
indicate the relative degree of importance attributed to 
any given project. 

Cost Bases 

The estimated costs for the various projects 
presented on Figure 7-1 reflect an ENR Index value taken 
at 2200 which is considered representative of costs in 
Boston for January 1975. 

As discussed in detail in Chapter 9 of Technical 
Data Vol. 2, Engineering Criteria , all costs include 
allowances for engineering and contingencies ranging from 
25 percent for interceptors to 50 percent for upgrading 
of facilities at sewage pumping stations. 

Costs for the construction of sewers, outfalls, 
treatment and pumping facilities that had been developed 
during the preparation of engineering reports for various 
communities involved in the study areas were used wherever 
applicable. In those cases, costs were updated from those 
presented in the reports by direct application of an ENR 
adjustment factor. 



7-1 



SCWER SECTION 



auihoriiaiion by legislaiure 

us oh huor siudy projicis 1 ' 1 

sludge managemeni 
(primary) 

111 ANALYSIS (souih SYSTEM!* 5 ' 

OORCHESIER BAY 
COHt. S. Off SHOWS 

III ANALYSIS WORM SYSIEM1< 5 > 

H I PRIMARY til. 

IIHCL. OUIIALL) 

I. PRIMARY IIP 

N.I- SECONDARY [XI. 

1. SECOHDARY ill. 

SLUOCl MANAGEMENI ISECOHOARYI 

MIODLl CHARLES R. H.H.I P. 



1,012.1 

SO. 536. C 



150.000.1 
28,091.1 
49.600,1 
II. 100.1 
6U. 700.1 



CHARUS R. COMB S OVERFLOWS 
HEPOHSEF S C0R8 5 0P18IIOWS 



8 LOHIR BRAIHIREE 
COM S 

9 BRAIHIREl HEYMOUIH 
PS 

jo •>n>.n i " 
ii siouchwh in s 

12 HALPOLI 111 !. 

13 HO CHARLfS ME1R0 



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FIG. 7-1 
MDC CONSTRUCTION STAGING PROGRAM 
FOR WASTEWATER MANAGEMENT 
PROJECTS- RECOMMENDED PLAN 



The cost estimates for items in each of the major 
categories covered in the various chapters of this report 
are discussed in detail in each of the respective Technical 

Data Volumes. 

Annual Operation and Maintenance Costs 

The costs associated with the annual operation and 
maintenance of the various facilities that appear in the 
Construction Staging Program and as discussed in detail 
in the appropriate Technical Data Volumes are summarized 
for the years 1980, 1990 and 2000 in Table 7-1. 



TABLE 7-1. SUMMARY OF ANNUAL OPERATION AND 
MAINTENANCE COSTS 

Year Annual cost 

1980 $13,^04,000 

1990 27,543,000 

2000 29,507,000 



These costs, which are all based on January 1975 
prices, reflect the upgrading or addition of new facili- 
ties in the various years as indicated In the Construction 
Staging Program, Figure 7-1, and relate to the treatment 
plants, interceptors and combined sewer overflow regulation 
facilities . 

Cost Apportionment and Allocation 

On the basis of the selected methods of cost appor- 
tionment and allocation described in Chapter 8, the follow- 
ing tables present the percentages of cost to be apportioned 
to communities and allocated to those sources of pollution 
for which treatment facilities are designed. 

Distribution of Capital Costs . Capital costs 
presented on Figure 7-1, would be distributed to flow (Q), 
BOD and SS as shown in Table 7-2. Although the satellite 
plants are designed for removal of additional parameters, 
such as phosphorus, and for reduction of oxygen demand 
through conversion of ammonia, such costs are allocated to 
flow in order to permit apportionment of all costs to all 
users uniformly. 



7-3 



TABLE 7-2. ESTIMATED PERCENT OF CAPITAL COSTS 
DISTRIBUTED TO FLOW, BOD AND SS FOR THE 
RECOMMENDED FACILITIES 



Facility 



Percent of cost attribu ted to 
EOD 



Flow 



SS 



WWTP 

Deer Island 

Primary expansion 
Secondary extension 

Nut Island 

Primary expansion 
Secondary extension 
Outfall extension 

Middle Charles 

Upper Neponset 

Sludge management 

Primary 
Secondary 

Pumping stations 

Interceptors 

Combined sewers 

I/I analysis 



69.2 
9.1 






100 

100 

100 

100 



13.5 
68.8 



17.3 
22.1 



77.5 
21.7 
00 


5.7 

58.8 



16.8 

19.5 



38.2 


37.0 


24.8 


37.0 


37.6 


25.4 




33 


100 
67 



























Distribution of Operation and Maintenance Costs . 
Table 7-3 shows the distribution of operation and mainte- 
nance costs as presented in Table 7-1 on the same basis as 
capital costs for three selected years. 

Apportionment of Costs 

Uniform apportionment of costs to communities is the 
recommended plan in Chapter 8. In this way, costs are 
apportioned to communities on equal rates irrespective of 
location or use of a facility. Such apportionment of costs 



7-4 



to communities on the basis of contributing design flow, 
BOD and SS for the selected years of 1980, 1990 and 2000 
are shown in Table 7-^. 



TABLE 7-3. DISTRIBUTION OF OPERATION AND 
MAINTENANCE COSTS TO FLOW, BOD AND SS 



Percent of cost attributed to 



Year 



1980 

1990 
2000 



Flow 


BOD 


SS 


79.1 


2.6 


18.3 


66.1 


21.7 


12.2 


65.2 


22.1 


12.7 



Allocation of Costs to Industries 

In conformance with the recommended allocation of 
costs, industries would pay their share of uniform costs 
on the basis of flow, BOD and SS. 

Determination of this industrial share is complex 
and requires detailed knowledge of each facility, its 
operating rules and future plans. In order to provide 
estimates for the industrial component with regards to 
industrial cost recovery, major industries were surveyed 
as discussed in Technical Data Volumes 2 and 3. Table 7-5 
presents the estimated costs attributable to major indus- 
trial flow, BOD and SS for each community as a percent of 
the community total. 



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7-9 



CHAPTER 8 
FINANCING AND MANAGEMENT 



General 

This chapter summarizes the key components of the 
financing and management aspects of the Recommended Plan. 
Detailed discussions on this are presented in Technical 
Data Vol. 12, Financing and Management . 

F inancing 

Recommendations are made on more equitable methods 
of charges and on taking advantage of MDC ' s status as a 
State department in securing loans along with changes 
necessary to fulfill eligibility requirements for State 
and Federal grants. 

Apportionment . A uniform basis is recommended 
for apportioning costs to member municipalities. Under 
this concept, all municipalities pay at the same rate for 
wastewater management services irrespective of their loca- 
tion and their use of various sewerage and treatment 
system components. On this basis, municipalities served 
by advanced treatment plants will pay at the same rate as 
those served by the Deer and Nut Island treatment plants. 
Similarly, apportionment of combined sewer overflow regu- 
lation costs would be on a uniform basis to all member 
municipalities . 

Allocation . Within a municipality, allocation of 
costs to the various users of the system would be on the 
basis of the quantity and strengths of wastes discharged. 
Determination of such quantities would be through esti- 
mates and measurements. Significant waste discharges 
would be measured and sampled and those of lesser signi- 
ficance would be estimated and could be categorized into 
user classes. 

Although water consumption is considered as the 
most appropriate measure of estimating waste contributions 
by the less significant dischargers, population may be 
used to estimate the domestic component of a municipality's 
contribution. Other categories may be related to domestic 
dischargers in the form of surcharges or population 
equivalents. 



8-1 



Distribution . The recommended measures for distri- 
buting costs to the various users are flow, BOD and SS . 
However, distribution of existing debt service (as of June 
30, 1975) should be on the basis of flow only. 

Operations . It is recommended that MDC remain a 
wholesaler of services with each municipality responsible 
for collecting charges from individual users. 

In terms of borrowing, the present system of utiliz- 
ing the State Treasurer's borrowing capacity is recommended 
to take advantage of favorable interest rates. 

Management 

Major recommendations in the organizational struc- 
ture are geared towards giving MDC more independence from 
Legislature controls by shifting these to controls by 
member municipalities, but still have MDC retain the State 
department posture and benefits. 

Leadership . Modification of the five member 
commission structure is recommended to a single commis- 
sioner responsible for leadership and administration. 

Also recommended is the freeing of MDC from the 
need for project-type appropriations by the Legislature 
to be replaced by overall program authorizations. This 
is needed to allow MDC the flexibility for responding to 
changing- requirements and high priority problems and 
needs of member cities and towns. 

A municipal advisory committee (MAC) is proposed to 
provide local input for program design, establishment of 
regulations and community coordination. MAC's authority 
would be to approve budgets and rules and regulations. 
However, its prime function would be to insure MDC ' s 
regional identity with the Legislature and member 
municipalities . 

Service Area . Enlargement of the MSD from its 
present 43 member municipalities to 51 municipalities is 
proposed along with provision for extraterritorial author- 
ity to assist other communities with technical and 
operational services. 

Organization . Internal organization changes are 
proposed to provide the Commissioner with the ability to 
plan, implement and manage effectively the proposed plan. 



8-2 



Development of subdistricts for operation of each 
of the proposed service areas is considered advantageous 
to provide better responsiveness to local community needs. 

Authority . Recognizing the more complex nature of 
wastewater treatment systems to be implemented along with 
a more stringent requirement for good performance, increased 
authority by the MDC is proposed over the operation of 
local sewerage systems. 

MDC Identity . In spite of the concern for insuring 
MDC ' s role as a regional entity, it is proposed that the 
District remain as a State Department to retain the advan- 
tages of stature and financial resource availability. 



8-3 










EXISTING MUNICIPAL SEWER 

@ CONSTRUCTION SEQUENCE NUMBER 

LH] ON-GOING PROJECTS 



FIG. 4-2 

COMMONWEALTH OF MASSACHUSETTS 

METROPOLITAN DISTRICT COMMISSION 

INTERCEPTOR RELIEF REQUIREMENTS 

AND EXTENSION SEWERS 

RECOMMENDED PLAN 

OCTOBER, 1975 



,©■* 






• WAKEBELD TRUNK SEWER 

4®] 



METRO.SEWER 



CHELSEA BRANCH SEWER 

REVERE EXTENSION SEWER 



■fewi^ 




IVORTH METRO SEWER 

!0P 




WINTHROP TERMINAL FACILITY 
DEER ISLAND WWTP 



% 




' 



/ 



m 



6000 12000 



SCALE IN FEET 




PROPOSED EXTENSION SEWER 

— — — EXISTING MUNICIPAL SEWER 

© CONSTRUCTION SEQUENCE NUMBER 

LH] ON-GOING PROJECTS 

■ PUMPING STATION OR 

WASTEWATER TREATMENT PLANT 



l'^ WINTHROP TERMINAL FACILITY 
DEER ISLAND WWTP 








j 


<h 












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FIG. 4-2 

COMMONWEALTH OF MASSACHUSETTS 

METROPOLITAN DISTRICT COMMISSION 

INTERCEPTOR RELIEF REQUIREMENTS 

AND EXTENSION SEWERS 

RECOMMENDED PLAN 

OCTOBER, 1975